Add a global filter to fs.walk.Walker

[atollk]

fs.walk.Walker can take filter and exclude parameters to include/exclude certain file base names, as well as filter_dirs and exclude_dirs parameters to include/exclude entire directories.

My suggestion is to introduce two new parameters, filter_glob and exclude_glob, to work on arbitrary path objects. This would make working with filters mixed of both directories and files much easier.

For example, consider a file system with three files:

foo/a.py
foo/b.py
bar/a.py

Walking over all files except for foo/a.py is, afaik, impossible with the current Walker functionality. My suggestion would allow for:

fs.walk.Walker(filter_glob=["/"], exclude_glob=["/foo/a.py"])