We introduce wasm types to Turbofan. They are represented by a new
subtype of {TypeBase}.
Types are attached to nodes during graph generation, as nodes are
assigned to wasm values. Therefore, phi nodes corresponding to merges
are not typed. Missing types will be computed, and assigned types will
be narrowed as much as possible, in a retyping phase that will be
introduced later.

Bug: v8:7748
Change-Id: I943559cf1d512edfab3bb2d22f8748c072cb1911
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3660248Reviewed-by: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80778}