In fond memory of kPossiblyBackgroundSerialized, this CL adds a new
subtype of kNeverSerialized called NeverEverSerialized. Such refs are
never ever serialized, i.e. not even when concurrent inlining is
disabled.

The first Ref in this category is RegExpBoilerplateDescriptionRef.

The intent is to gradually transition all kNeverSerialized refs to
NeverEverSerialized and then remove NeverEverSerialized (making it the
default behavior).

Bug: v8:7790
Change-Id: I8741a94212426a773ec3dc20758a41cb89f13368
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2947415
Auto-Submit: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75064}