Add files.copy operation

[EricDriussi]

Adds copy operation suggested in #1121. Any and all feedback is welcome!

• Pull request is based on the default branch (3.x at this time)
• Pull request includes tests for any new/updated operations/facts
• Pull request includes documentation for any new/updated operations/facts
• Tests pass (see scripts/dev-test.sh)
• Type checking & code style passes (see scripts/dev-lint.sh)

[DonDebonair]

Why should this raise an OperationError. For copy() to be idempotent, the destination file existing, should just be a noop right? Alternatively, you could compare hashes to see if the src file has changed.

[EricDriussi]

Indeed a noop would be a better fit here, although I still feel that an error should be raised in case dest_file_path already exists and is different from src. So maybe something like this?

    if dest_file_exists and not overwrite:
        if _file_equal(src, dest_file_path):
            host.noop(f"{dest_file_path} already exists")
        else:
            raise OperationError(f"{dest_file_path} already exists and is different than src")

Or maybe there's a better way to handle that case?

Also, in the snippet I use the _file_equal function, but that seems to be intended for local-remote hash comparisons.
Are you aware of any functions that might better fit this use case? Should I just create a new internal function based on this one for remote-remote hash comparison (what could be a nice name for it?)?

[DonDebonair]

I agree with you that the noop should only happen when the existing file at destination is the same.

I don't know if the _file_equal function can be used for remote-remote hash comparisons. @Fizzadar do you know?

[Fizzadar]

Indeed _file_equal is for local <> remote, a new function seems best here, basically fact x2 and compare.

[EricDriussi]

Hey! Sorry it took me forever to get back to this...
I implemented the changes mentioned here, added/fixed tests and skipped the Windows CI (simply due to me not having a Windows machine to ensure the tests work before pushing).

Also, in the new _remote_file_equals function, I followed the same fallback logic I saw in _file_equals regarding the checksum comparison.
I'm not quite sure if this is correct so please let me know if there's anything that needs to be updated before merging.

[Fizzadar]

@EricDriussi no worries re:times, thank you for finishing this up! Looks good to me will leave for Daan to have a double check too.