Add initial support for ty type hinting

[Repiteo]

A minimal baseline for utilizing ty as a type hinting tool within the codebase. This has technically already been possible, but a few key settings added to pyproject.toml help clean things up even further:

• Specify our (upcoming) 3.9 minimum.
• Don't assume a specific platform in intellisense; will try to support any/all.
• Pass "./testing/framework" as a module path to cleanup the overwhelming majority of error noise.
• Add explicit warnings for 2 default-ignored rules (blanket-ignore-commen & missing-type-argument), as the areas of the engine with type hints already have these accounted for.

Contributor Checklist:

• I have created a new test or updated the unit tests to cover the new/changed functionality.
• I have updated CHANGES.txt and RELEASE.txt (and read the README.rst).
• I have updated the appropriate documentation

[mwichmann]

Since the new entries are specific to ty, I can't see any problem.