Outset:
The more advanced features of OutSet are no longer used, thus the
rename to DynamicBitSet to reflect its current purpose.

BoyerMoorePositionInfo:
Use bitset backing store in BoyerMoorePositionInfo (previously this
was based on a (statically-sized) ZoneList<bool>).

Bug: v8:9359
Change-Id: I40ca89467ae90ee90c616be5fd0d51e54e94e157
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1664064
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62277}