rust-filepatterns: call new Rust implementations from Python This change adds the import to the `rust-cpython` bindings and uses them when appropriate. A wrapper function has been defined in the case of `_regex` to keep this patch simple. Differential Revision: https://phab.mercurial-scm.org/D6273

rust-filepatterns: add `rust-cpython` bindings for `filepatterns` This change adds the `rust-cpython` interface for top-level functions and exceptions in the filepatterns module. Contrary to the Python implementation, this tries to have finer-grained exceptions to allow for better readability and flow control down the line. Differential Revision: https://phab.mercurial-scm.org/D6272