LUCENE-10526: add single method to mockfile to wrap a Path

[rmuir]

Currently "new FilterPath" is called from everywhere, making it impossible for a mockfilesystem to use a custom subclass.

See JIRA for full description.

The use case here is to e.g. allow WindowsFS to wrap with a custom subclass that checks for special characters that windows doesn't allow. But today it can't do that since there is code everywhere doing the wrapping.

This PR adds a single method wrapPath() to FilterFileSystemProvider to do this wrapping, and refactors everything to use it.

[mikemccand]

This looks awesome @rmuir -- now we consistently call provider.wrapPath instead of new FilterPath allowing us to make improvements like LUCENE-10525 (properly blocking illegal windows-only filesystem characters) far easier. Thanks!!

[gautamworah96]

I left just one comment from my limited understanding of the mock FS APIs.
The plan described in the LUCENE-10525 JIRA does make sense. This opens up avenues to improve other FS systems with specific customizations as well (going well beyond the original motivation!).

[rmuir]

@gautamworah96 care to take another look? I think fixing the tiny nit was helpful to our tests. now it is easier for tests to wrap a path with one of these mock filesystems explicitly, as they don't have to deal with URI class or pass around FileSystem objects. thanks!

[gautamworah96]

LGTM. I mocked a bit of the WindowsPath locally and placing the filename checks there make sense.

[rmuir]

Thanks for reviewing, and good luck improving the act-like-Windows!