POC: docstring inheritance
Proof of concept for automatically inheriting docstrings, so we dont have to use `@Appender(parent_class.method.__doc__)` quite so much.

This doesnt handle `@Substitution`.  If we can make that work for the common case where we're just putting in the class name, we could get a _lot_ less verbose.

xref #31095, #31060.
Looks nice though I am actually -1 on inheriting docstrings compared to simplifying the existing Appender / Substitution decorators. I suppose my main argument is that not everything really can be inherited (ex: we sometimes inherit but change signature or semantics) so would end up having to revert back to Appender / Substitution anyway in some cases Closing to clear the queue