Extract Fabric event handlers from canonical props (#13024)

We need a different "component tree" thingy for Fabric.

A lot of this doesn't really make much sense in a persistent world but
currently we can't dispatch events to memoizedProps on a Fiber since
they're pooled. Also, it's unclear what the semantics should be when we
dispatch an event that happened when the old props were in effect but now
we have new props already.

This implementation tries to use the last committed props but also fails
at that because we don't have a commit hook in the persistent mode.

However, at least it doesn't crash when dispatching. :)