Issue description

Currently the predicate of lib.fileset.fileFilter only gets name, type (and soon hasExt).

There's no way to filter by the subpath/components of the file, something like this:

lib.fileset.fileFilter (file:
  lib.lists.hasSuffix [ "foo" "bar" ] file.components
) ./.

(hasSuffix currently also doesn't exist)

Some ideas:

• file.components :: [ String ]: File components, always at least one element for the file's name
• file.subpath :: String: The file's subpath
• file.dirComponents :: [ String ]: Directory components, can be empty for files in the root level
• file.dirSubpath :: String: Directory subpath, can be ./. for files in the root level

This feature request is the motivation behind #267384.

This issue is sponsored by Antithesis ✨