Strip out unnecessary dependencies

[techalchemy]

• Remove vistir and crayons
• Reimplement heavily relied-upon functionality
• Copy over vistir utilities used heavily in tests to avoid this as a
  test dependency as well
• Rewrite mocks that relied on vistir-specific invocations
• Regenerate lockfile
• Begins to address Reduce/Eliminate dependencies #78

Signed-off-by: Dan Ryan [email protected]

[ghost]

DeepCode's analysis on #62c39f found:

• ❌ 0 critical issues. ⚠️ 0 warnings and 8 minor issues. ✔️ 0 issues were fixed.

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[techalchemy]

Note that attrs forms the backbone of all of the classes used in the library, cached-property drives the performance gains i've managed to sneak out of it, and while packaging is largely used for type hints it's not a huge price to pay