This enhances sage_setup.find.find_extra_files to better support non-Python resources found in Python package sources. Previously it could include extra files found under build/cythonized, but now it can also include arbitrary files (including support for fnmatch patterns) that should be installed alongside a Python package. For example,

find_extra_files('sage.foo', '.', special_filenames=['*.html'])

will find any .html files under the ./sage/foo/ package.

This will be useful for #21732 and possibly other tickets.

This also adds a package_data variable in module_list.py that can list all non-Python resources on a per-package basis (using the same format as the standard package_data option to setup.py. This includes handling of package data in a way that's compatible with sage_setup.clean.clean_install_dir.

CC: @mkoeppe

Component: build

Author: Erik Bray

Branch/Commit: u/embray/build/package-data @ 5d30652

Issue created by migration from https://trac.sagemath.org/ticket/22655