Coalesce lifecycle deprecation warnings until the commit phase

[bvaughn]

Builds on top of PR #12083 and resolves issue #12044.

Coalesces deprecation warnings until the commit phase. This proposal extends the ReactDebugAsyncWarnings utility introduced in #12060 to also coalesce deprecation warnings.

New warning format will look like this:

componentWillMount is deprecated and will be removed in the next major version. Use componentDidMount instead. As a temporary workaround, you can rename to UNSAFE_componentWillMount.

Please update the following components: Foo, Bar

Learn more about this warning here:
https://fb.me/react-async-component-lifecycle-hooks

[sebmarkbage]

It can be a bit confusing that we warn for things that didn't commit. If something starts rendering and then gets aborted, and we commit something else, then it'll list those.

Ideally, it should probably be a new effect type that we can mark on the effect tag of each fiber so that we know to visit them and issue a warning of some sort. That would also avoid flushPendingDeprecationWarnings becoming an ever growing list of things to check for.

Another potential issue that internally we log these warnings. Those will go into tables that can't dedupe these since they will be unique combinations every time if they're aborted at different points.

[bvaughn]

Rebased on top of master now that #12083 has been merged.

[bvaughn]

Another potential issue that internally we log these warnings. Those will go into tables that can't dedupe these since they will be unique combinations every time if they're aborted at different points.

This shouldn't be an issue for us, right? We have the codemod (that I've already tested by running internally). It will be easy for us to remove the deprecated methods after we sync.