Fully type module (missing annotations)

[Avasam]

This is an issue to track openpack's missing type annotations'.
The package is marked as py.typed, but all modules are missing annotations for parameters and return types. This will lead to type errors downstream for any user of strict type checking whenever using any of this package's methods.

Refs:

• Expand type hints across projects skeleton#98
• Update mypy.ini from setuptools skeleton#136 (comment)
• Widespread mypy failures skeleton#143