abstractions/python: merge /usr/ and /usr/local/ rules, and add some new rules

This keeps all existing permissions, and adds a few that were out of sync:

• /usr/lib*/python3./lib-dynload/.so missed 3.1[0-9]
• /usr/lib/python3/... was missing, only /usr/local/python3/ was allowed

Also add several permissions:

• allow reading .so.
• allow directory listings in .../site-packages/
• allow reading various metadata files

These additions are based on denials seen on openSUSE Leap 15.3 with python 3.9.

I propose this patch for 3.0 and master.