ISSUE-1902 Fix Template::is_up_to_date contract

[rwielk]

https://github.com/pallets/jinja/issues/1902

Template::_uptodate type hints get supporting implementation

• fixes #1902

Checklist:

• [x] Add tests that demonstrate the correct behavior of the change. Tests should fail without the change.
• [X] Add or update relevant docs, in the docs folder and in code.
• [X] Add an entry in CHANGES.rst summarizing the change and linking to the issue.
• [X] Add .. versionchanged:: entries in any relevant code docs. (Opted against any change since this just fixes already expected behaviour from my POV)
• [X] Run pre-commit hooks and fix any issues.
• [X] Run pytest and tox, no tests failed.

Please hint me on where and how you want a test to get implemented for this, did not see an obvious place. (Example test in regressions added, perhaps it's good enough...)

[davidism]

See discussion in #1902 for close reason.