fix: Capture groups should be ignored in replace_all when literal=True

[corwinjoy]

Fixes #18238.
From the docs, (https://docs.pola.rs/api/python/stable/reference/expressions/api/polars.Expr.str.replace_all.html#polars-expr-str-replace-all), when literal=True, then capture groups should be ignored. As the docs say:

The dollar sign ($) is a special character related to capture groups. To refer to a literal dollar sign, use $$ instead or set literal to True.

Fix the Rust logic which did not apply this logic for multi-row replacement.

[corwinjoy]

Still a bit new at Rust. I ended up putting an if in the lambda when what I really wanted was to create the lambda I need once based on the literal. This is probably slightly slower, but I doubt it matters.

[ritchie46]

The lambda's will be different. So you must either put them behind an indirection or call iter_and_replace in the branches.

But here it won't really matter indeed.

[corwinjoy]

@adamreeve

[codecov]

Codecov Report

Attention: Patch coverage is 88.88889% with 1 line in your changes missing coverage. Please review.

Project coverage is 80.20%. Comparing base (00650b9) to head (0b506c5).
Report is 22 commits behind head on main.

Files with missing lines	Patch %	Lines
...rates/polars-plan/src/dsl/function_expr/strings.rs	88.88%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #19366      +/-   ##
==========================================
+ Coverage   80.02%   80.20%   +0.17%     
==========================================
  Files        1528     1523       -5     
  Lines      209871   209859      -12     
  Branches     2419     2434      +15     
==========================================
+ Hits       167954   168314     +360     
+ Misses      41366    40990     -376     
- Partials      551      555       +4     

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