Add more missing type hints to tests. (#15028)

changelog.d/15028.misc

mypy.ini

tests/handlers/test_oidc.py

tests/scripts/test_new_matrix_user.py

tests/server_notices/test_consent.py

tests/server_notices/test_resource_limits_server_notices.py

tests/test_federation.py

tests/test_utils/__init__.py

tests/test_utils/event_injection.py

tests/test_utils/html_parsers.py

tests/test_utils/logging_setup.py

tests/test_utils/oidc.py

tests/test_visibility.py

tests/unittest.py