bpo-31457: Don't omit inner ``process()`` calls with nested LogAdapters (GH-4044...

bpo-31457: Don't omit inner ``process()`` calls with nested LogAdapters (GH-4044) (#6568)

This used to be the case on Python 2.  Commit
212b590e118e3650b596917021ed9612a918180b changed the implementation for Python
3, making the `log()` method of LogAdapter call `logger._log()` directly.  This
makes nested log adapters not execute their ``process()`` method.  This patch
fixes the issue.

Also, now proxying `name`, too, to make `repr()` work with nested log adapters.

New tests added.
(cherry picked from commit ce9e62544571e7ade7186697d5dd065fb4c5243f)

Co-authored-by: Łukasz Langa <lukasz@langa.pl>