Feature request: add type hints

[Redmar-van-den-Berg]

Issue

I'm using hgvs-parser in a project that is using type hints, which causes errors because hgvs-parser itself does not have type hints:

 error: Skipping analyzing "mutalyzer_hgvs_parser": module is installed, but missing library stubs or py.typed marker  [import-untyped]
src/GTGT/models.py:7: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports

Workaround

Ignore modules missing type hints, by using the --ignore-missing-imports option in mypy.

Solution

Add type hints to the hgvs-parser project.