Inheritance overhaul

### What

Minimally do https://github.com/ethereum/solidity/issues/12665.
Beyond that consider introducing more advanced inheritance mechanisms. Some discussion is already in the forum.

### Resources

1. #12665
2. [Thoughts on override(A, B) syntax](https://forum.soliditylang.org/t/thoughts-on-override-a-b-syntax/767/10)

### Notes

It can be done independently of any other work if we have the time.

Start by reading issue #12665 and the linked forum discussion on override(A, B) syntax. Determine the minimum inheritance changes required by #12665 before considering broader inheritance mechanisms. Done means the requested minimum behavior is implemented and validated; the issue does not name files or tests to run.

Written by the indexing model from the issue text.