Make gramps.gen.lib.primaryobj typed

[bartfeenstra]

This PR:

• Adds type hints to everything in gramps.gen.lib.primaryobj, as well as any methods overridden in subclasses
• Uses typing.override to help mypy ensure subclasses override methods correctly, and for them to inherit the parents' docstrings (hence the large number of removals).

[Nick-Hall]

This is a Python 3.12 feature so we may need to install typing_extensions for this to work in older versions.

Yes. The code should run on python 3.10 in the master branch.

[bartfeenstra]

This is a Python 3.12 feature so we may need to install typing_extensions for this to work in older versions.

Yes. The code should run on python 3.10 in the master branch.

Do we want CI builds for that so that people like me don't accidentally break things?

[Nick-Hall]

The CI is running 3.10 in the master branch and I run 3.13 locally.

[bartfeenstra]

Oh right, I confused the linter action (which passed) with the CI one which is the one that actually runs mypy (soz!). I updated the PR to use typing_extensions so this should pass on 3.10 now.