`TypedDict` inheritance is weird in a way that Sphinx can't deal with easily. `TypedDict` isn't actually a class itself, and things which inherit from it get flattened to inherit directly from `dict` and have a variety of annotation-only properties for the data inside. Sphinx can find any documentation attached to those properties, but when one inherits from another, the documentation for any properties coming from the parent class gets lost. This change adds some custom documenter classes to detect when we have inherited TypedDict members and to scan up the chain using `__orig_bases__` to find docs for inherited members. This requires Python 3.11+ if using `typing.TypedDict`. It works for all versions when using `typing_extensions.TypedDict`. Testing Done: - Built the RBTools documentation with this and saw that all of our new `*Params` definitions had documentation for all members, including ones inherited from parent classes. - Ran unit tests.