chcon: Handle repeated flags and overrides between --no-XXX and --XXX

[BenWiederhake]

This PR changes and tests three things:

• Accept --no-dereference and --dereference in any order, use the last occurrence.
• Accept --no-preserve-root and --preserve-root in any order, use the last occurrence.
• Accept repetitions of everything, flags and arguments like --user.

All three of these are GNU behavior bugs, i.e. GNU does it differently, and uutils wants to handle it like GNU does.

This is work towards #5998.

[BenWiederhake]

Changes since last push:

• Mark "vvRRHHLLPP" as a non-typo. The spellchecker is very noisy, is it really worth it?
• Nothing else.

[tertsdiepraam]

Mark "vvRRHHLLPP" as a non-typo. The spellchecker is very noisy, is it really worth it?

It saves us a bunch of review time and helps with consistency across the project. Installing it locally helps a lot, because then you can just see the spelling errors before committing.

[BenWiederhake]

I did install it locally, and it already saved me a CI cycle, but it doesn't currently run automatically on each commit. Would a PR to add it to pre-commit be welcome? (Of course, not everyone has it installed, the script / invocation would have to deal with that.)

[tertsdiepraam]

Let's open an issue for doing CI checks locally. I'm not really sold on mandatory pre-commit hooks, but I'd love to have a Justfile or something like that to do all the checks (spelling, fmt, clippy, cargo check, cargo deny) locally before pushing.

I might even try doing that with nix or something, so that all the tools are installed automatically. We have lots of options.

[github-actions]

GNU testsuite comparison:

Congrats! The gnu test tests/chown/preserve-root is no longer failing!