Also:
- Refactor the ValueSerializer tests using raw data, so that we test all
valid versions for each test (not only one hard-coded one)
- Mark some tests as backwards compatibility tests, to make it less
likely that somebody updates them not realizing they are backwards
compatibility tests.

Bug: v8:11111, v8:12532
Change-Id: I670849de07742c8d442249ef4f013781e4ee9255
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3386802Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78681}