Replace uses of WordEqual on two tagged representation nodes with a new
TaggedEqual helper, which on pointer compressed configs only compares
the bottom 32-bits of the word. We no longer allow using WordEqual on
anything not known to be a WordT (i.e. Node* or TNode<Object>).

In the future, this may allow us to ignore the top bits of an
uncompressed Smi, and have simpler decompression, though this patch is
not sufficient for such a change.

As a necessary drive-by, TNodify a bunch of stuff.

Bug: v8:8948
Change-Id: Ie11b70709e5d3073f12551b37b420a172a71bc99
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1763531
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63372}