AliasDB interface cleanup (#15656)

AliasDB interface cleanup (#15656)

Summary:
This is the first of several PRs to simplify AliasDb usage.
- Hide the concept wildcards from users. They are too hard to think about and too easy to forget about.
- Start moving "mutability-safe" graph mutation methods into AliasDb (right now, the various methods that deal with topological move).

Eventually I want to create a "mutability-aware" handle to the graph. If you only use that handle to transform the graph, you can be sure that all transformations are safe with respect to mutability.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15656

Differential Revision: D13615492

Pulled By: suo

fbshipit-source-id: 5c39a157b4ea76f1f976315d06a314a89cc4f22f