Support Python 3.12 TypeAlias syntax

[JasonGrace2282]

Python 3.12 introduced some syntax to define TypeAlias's that looks like

type InteralPoint3D = npt.NDArray[ManimPointDType]

Annoyingly for us, this is represented in AST as a TypeAlias node instead of the AnnAssign node we're used to. As such, the autoaliasattr directive does not work with this syntax, and type aliases defined using this syntax are not documented.

While manim still has some time before Python 3.12 becomes the minimum supported version and we can begin using this syntax, it would be nice to have it implemented so that fewer worries occur when that eventually happens.