Add a --deopt-to-baseline flag, on by default, which allows returning to
sparkplug code when deoptimizing.

However when we turn this off, no longer deoptimizing to baseline code
means we can omit marking most bytecodes as valid jump targets. Leaving
just OSR and exception handling entry points.

This reduces the baseline code size by ~18% on Arm64.

Bug: v8:13082
Change-Id: I5b5a6679465807d7fe812cb977464167efffa7ab
Cq-Include-Trybots: luci.v8.try:v8_linux_arm64_cfi_rel_ng
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3785006Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Pierre Langlois <pierre.langlois@arm.com>
Cr-Commit-Position: refs/heads/main@{#82266}