dillon1000/react

Remove remaining references to effect list (#19673)

* Remove `firstEffect` null check

This is the last remaining place where the effect list has semantic
implications.

I've replaced it with a check of `effectTag` and `subtreeTag`, to see
if there are any effects in the whole tree. This matches the semantics
of the old check. However, I think only reason this optimization exists
is because it affects profiling. We should reconsider whether this
is necessary.

* Remove remaining references to effect list

We no longer use the effect list anywhere in our implementation. It's
been replaced by a recursive traversal in the commit phase.

This removes all references to the effect list in the new fork.