Implement new glob recipe

[kylewlacy]

Closes #79

This PR implements the new glob recipe type, which takes a directory recipe and a list of patterns, and bakes to a new directory filtered down based on the list of patterns.

Even though Brioche already uses globset for glob matching, I ended up using Wax to match glob patterns for the glob recipe. This is because globset (and most other glob matching libraries) use std::path::Path somewhere in the pipeline, which might lead to different behavior depending on the host platform. On the other hand, Wax is meant to be portable across platforms, so it's a good fit for this use case

One limitation around Wax is that the paths to match against must be &strs, which mean they must be valid UTF-8. Brioche currently doesn't enforce that filenames are UTF-8, so paths in artifacts are converted using String::from_utf8_lossy, which means that wildcards will even work with invalid UTF-8 sequences in paths (this also means a glob pattern can use the Unicode replacement character (�) to match an invalid UTF-8 byte)

I also disallowed any glob patterns from containing !. As far as I can tell, Wax doesn't handle "negative patterns" natively, so I wanted to reserve ! in case we wanted to support gitignore-style syntax for excluding specific files in the future