Fixup #14021 (Add file mode specifier to PathMatch)

[glankk]

This is an addendum to #7645 that adds the ability to specify directory-only matching in PathMatch patterns with a trailing slash. I originally didn't add this because I wanted to keep PathMatch purely syntactic, and this feature seemed like it would require filesystem calls in the PathMatch code.

This PR solves that problem by lifting the responsibility of file mode checking to the caller, thus keeping PathMatch purely syntactic while still supporting directory-only matching.

Previously /test/foo/ would match /test/foo even if foo is a regular file. With this change the caller can specify the file mode of the file named by the provided path, and /test/foo will only match when the file mode is directory.

The semantics of patterns that do not have a trailing slash is unchanged, e.g. /test/foo still matches /test/foo/ and /test/foo/bar.cpp, regardless of the file mode.

Also adds some more tests.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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[danmar]

would it make sense to tweak the manual a bit?

[danmar]

I merge this with the assumption that the manual will be updated soonish..