In particular, this CL adds support for:
- exception handling
- source positions
- OSR
- various numeric operations and conversions

Since the test suite now passes with `--turboshaft`, this also adds a
new variant for Turboshaft and enables it on some bots.

Bug: v8:12783
Change-Id: Ia2dd2e16f56fc955d49e51f86d050218e70cb575
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3669251Reviewed-by: Darius Mercadier <dmercadier@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81074}