Fix Any subclassing in fpdf2

[Avasam]

Can't reference fontools directly because it does not have a py.typed marker (it's only partially typed).
It would be a bit overkill anyway.

Fixes an Any subclassing error in fpdf2 by shimming the needed fontools types.

Ref: #9491

[github-actions]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉

[Avasam]

Unlike in #9525, all type definitions here are subclasses of each-other. And parameters use standard types. So the whole shim file makes more sense for the full BasePen structure.