bpo-46542: test_lib2to3 uses support.infinite_recursion() (GH-31035)

* bpo-46542: test_lib2to3 uses support.infinite_recursion()

Fix a Python crash in test_lib2to3 when using Python built in debug
mode: limit the recursion limit.

The test_all_project_files() test of test_lib2to3 now uses the
test.support.infinite_recursion() context manager when processing the
infinite_recursion.py file to prevent a crash when Python is built in
debug mode.

The two test_all_project_files() tests now use subTest() and log the
refactored/parsed filename (if test_lib2to3 is run in verbose mode).

* Update Lib/lib2to3/tests/data/infinite_recursion.py

Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>

Co-authored-by: Łukasz Langa <lukasz@langa.pl>
Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>
(cherry picked from commit ee0ac328d38a86f7907598c94cb88a97635b32f8)

Co-authored-by: Victor Stinner <vstinner@python.org>