Comments for LINQ generated code does not contain inherited attributes/elements

Previously, the generation for the code relied on runtime information which would automatically get the inherited value. With the move to using source generators, this is not the case and is not straightforward with the current data structure.

The direction to investigate here would be:

- Create a lookup in OpenXmlGeneratorServices that would search the types given `SchemaType.BaseClass`
- Update the backend to not use a class name in `SchemaType.BaseClass` but rather a QName

_Originally posted by @twsouthwick in https://github.com/dotnet/Open-XML-SDK/issues/1345#issuecomment-1459157916_