fix: add &>> implementation

[reubeno]

&> is already implemented; this adds the append version of it.

Fixes #102

[github-actions]

Test Results

403 tests   388 ✅  1m 19s ⏱️
 64 suites   15 💤
  8 files      0 ❌

Results for commit f9bbdba.

[github-actions]

Performance Benchmark Report

Benchmark name	Baseline (ns)	Test/PR (ns)	Delta (ns)	Delta %
expand_one_string	3463 ns	3462 ns	-1 ns	🟢 -0.03%
instantiate_shell	61434 ns	60966 ns	-468 ns	🟢 -0.76%
instantiate_shell_with_init_scripts	27431918 ns	27532151 ns	+100233 ns	🟠 +0.37%
parse_bash_completion	5490730 ns	5504909 ns	+14179 ns	🟠 +0.26%
parse_sample_script	8893 ns	8932 ns	+39 ns	🟠 +0.44%
run_echo_builtin_command	94457 ns	94544 ns	+87 ns	🟠 +0.09%
run_one_builtin_command	113790 ns	111536 ns	-2254 ns	🟢 -1.98%
run_one_external_command	1931943 ns	1931440 ns	-503 ns	🟢 -0.03%
run_one_external_command_directly	994876 ns	997540 ns	+2664 ns	🟠 +0.27%

Code Coverage Report

Package	Base Coverage	New Coverage	Difference
/home/runner/work/brush/brush/brush-core/src/arithmetic.rs	🟢 99.01%	🟢 99.01%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtin.rs	🔴 31.21%	🔴 31.21%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/alias.rs	🟢 83.87%	🟢 83.87%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/bg.rs	🔴 0%	🔴 0%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/break_.rs	🟢 90%	🟢 90%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/builtin_.rs	🟢 100%	🟢 100%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/cd.rs	🟢 88.57%	🟢 88.57%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/colon.rs	🟢 100%	🟢 100%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/command.rs	🟢 93.26%	🟢 93.26%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/complete.rs	🔴 21.48%	🔴 21.48%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/continue_.rs	🟢 90%	🟢 90%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/declare.rs	🟢 82.83%	🟢 82.83%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/dirs.rs	🟢 90.48%	🟢 90.48%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/dot.rs	🟢 95.65%	🟢 95.65%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/echo.rs	🟢 86.84%	🟢 86.84%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/enable.rs	🟢 91.07%	🟢 91.07%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/eval.rs	🟢 100%	🟢 100%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/exec.rs	🟢 90.32%	🟢 90.32%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/exit.rs	🟢 100%	🟢 100%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/export.rs	🟢 88.73%	🟢 88.73%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/false_.rs	🟢 100%	🟢 100%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/fg.rs	🔴 0%	🔴 0%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/getopts.rs	🟢 97.7%	🟢 97.7%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/help.rs	🟢 91.86%	🟢 91.86%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/jobs.rs	🔴 41.86%	🔴 41.86%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/kill.rs	🔴 0%	🔴 0%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/let_.rs	🟢 100%	🟢 100%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/mod.rs	🟢 94.61%	🟢 94.61%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/popd.rs	🟢 94.12%	🟢 94.12%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/printf.rs	🟢 91.18%	🟢 91.18%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/pushd.rs	🟢 91.3%	🟢 91.3%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/pwd.rs	🟢 89.47%	🟢 89.47%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/read.rs	🟠 73.53%	🟠 73.53%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/return_.rs	🟢 83.33%	🟢 83.33%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/set.rs	🟢 76.64%	🟢 76.64%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/shift.rs	🟢 100%	🟢 100%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/shopt.rs	🟢 88.39%	🟢 88.39%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/test.rs	🟢 100%	🟢 100%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/trap.rs	🟢 83.15%	🟢 83.15%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/true_.rs	🟢 100%	🟢 100%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/type_.rs	🟢 90.27%	🟢 90.27%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/umask.rs	🔴 0%	🔴 0%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/unalias.rs	🔴 0%	🔴 0%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/unimp.rs	🔴 0%	🔴 0%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/unset.rs	🟢 94.64%	🟢 94.64%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/builtins/wait.rs	🟢 85.71%	🟢 85.71%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/commands.rs	🟢 92.86%	🟢 92.86%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/completion.rs	🔴 42.49%	🔴 42.49%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/env.rs	🟢 87.85%	🟢 87.85%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/error.rs	🔴 25%	🔴 25%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/escape.rs	🔴 14.91%	🔴 14.91%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/expansion.rs	🟢 95.95%	🟢 95.95%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/extendedtests.rs	🟠 64.15%	🟠 64.15%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/files.rs	🟠 66.67%	🟠 66.67%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/functions.rs	🟢 100%	🟢 100%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/interp.rs	🟢 93.11%	🟢 93.14%	🟢 0.03%
/home/runner/work/brush/brush/brush-core/src/jobs.rs	🔴 41.45%	🔴 39.38%	🔴 -2.07%
/home/runner/work/brush/brush/brush-core/src/keywords.rs	🟢 96.88%	🟢 96.88%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/namedoptions.rs	🟠 52.34%	🟠 52.34%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/openfiles.rs	🔴 46.15%	🔴 46.15%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/options.rs	🟢 100%	🟢 100%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/patterns.rs	🟢 96.96%	🟢 96.96%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/prompt.rs	🟢 78.48%	🟢 78.48%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/regex.rs	🟢 100%	🟢 100%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/shell.rs	🟢 78.44%	🟢 78.61%	🟢 0.17%
/home/runner/work/brush/brush/brush-core/src/tests.rs	🟠 50%	🟠 50%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/traps.rs	🟠 50%	🟠 50%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/users.rs	🔴 16.13%	🔴 16.13%	⚪ 0%
/home/runner/work/brush/brush/brush-core/src/variables.rs	🟢 79.91%	🟢 79.91%	⚪ 0%
/home/runner/work/brush/brush/brush-interactive/src/interactive_shell.rs	🟢 77.78%	🟢 77.78%	⚪ 0%
/home/runner/work/brush/brush/brush-parser/src/arithmetic.rs	🟢 100%	🟢 100%	⚪ 0%
/home/runner/work/brush/brush/brush-parser/src/ast.rs	🔴 29.36%	🔴 29.11%	🔴 -0.25%
/home/runner/work/brush/brush/brush-parser/src/error.rs	🟢 76.92%	🟢 76.92%	⚪ 0%
/home/runner/work/brush/brush/brush-parser/src/parser.rs	🟢 99.73%	🟢 99.73%	⚪ 0%
/home/runner/work/brush/brush/brush-parser/src/pattern.rs	🟢 100%	🟢 100%	⚪ 0%
/home/runner/work/brush/brush/brush-parser/src/prompt.rs	🟢 100%	🟢 100%	⚪ 0%
/home/runner/work/brush/brush/brush-parser/src/test_command.rs	🟢 100%	🟢 100%	⚪ 0%
/home/runner/work/brush/brush/brush-parser/src/tokenizer.rs	🟢 96.36%	🟢 96.36%	⚪ 0%
/home/runner/work/brush/brush/brush-parser/src/word.rs	🟢 100%	🟢 100%	⚪ 0%
/home/runner/work/brush/brush/brush-shell/src/main.rs	🟠 71.63%	🟠 71.63%	⚪ 0%
Overall Coverage	🟢 78.57%	🟢 78.53%	🔴 -0.04%

Minimum allowed coverage is 0%, this run produced 78.53%