Templatize the VLQ methods to avoid std::function overheads, and add a
few optimisations (small value fast path, split writing and tagging).

Change-Id: I840d60c972916d1a6023c8ea2a67bbd540f2d159
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2839554
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Patrick Thier <pthier@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74081}