Add proper typehints

[RobotSail]

We should increase our usage of type-hints throughout the codebase so that developers, language servers, and linting all have a clear idea of what kinds of values get passed around and where.

[ktam3]

Additional discussion required - as part of SDG reconciliation efforts, this issue is dependent on the changes made during that and will be put on hold until those discussions are complete and a finalize design and process is approved.