feat: properly remove temporary files leftover after running tests

[cryptonemo]

Take 2: It took a while to track down which tests were leaving around .tmp* directories and files in the TEMPDIR after the test suite was run, but it appears that this resolves them all across normal and 'ignored' tests.

In short, if there are any open files/dirs remaining when TempDir is scoped out, a deletion is silently omitted. This code more explicitly cleans up some temporary artifacts in order to ensure everything is removed and closed before that happens.

[DrPeterVanNostrand]

I'm not sure that I understand putting cache_dir.close() behind an if. fs::remove_dir will return Ok if cache_dir contains no files and is successfully removed (which would cause cache_dir.path().exists() to be false), or it will return an Err if cache_dir contains files.

Would something like the following also work without putting tempdir closing behind an if statement?

Suggested change

	if std::fs::remove_dir(cache_dir.path()).is_ok() && cache_dir.path().exists() {
	let _ = cache_dir.close();
	}
	let _ = std::fs::remove_dir_all(cache_dir.path());
	let _ = cache_dir.close();

[cryptonemo]

Pretty sure I tried that and it didn't work (would sometimes error on the second line).

[cryptonemo]

Also, if you can find a different way to solve it, it would be appreciated. The goal is just for it to 1) not cause an error, and 2) be gone after the run. Took me a while to get that going and I agree it's weird (but works).

[DrPeterVanNostrand]

Oh, that is weird. If you've already tried alternatives to the if and the tests' temp-files weren't fully removed, then the PR looks good to me.