Use the new jobs API for WebAssembly compilation. This avoids having to
schedule as many background tasks as there are worker threads. Instead
the one job specifies the maximum concurrency, which changes dynamically
as new compile jobs become available.
This also avoids the artificial deadline we used to ensure that other
tasks get some share of the CPU resources if needed.

Even though this CL moves actual wasm function completely over to the
Jobs API, other similar tasks (like wrapper compilation) are still using
the Task API and need to be ported in a follow-up CL.
Also, we are still using the same priority for baseline compilation and
tier up. We should split this in a follow-up CL to have two jobs with
different priorities. This will also allow us to only block on baseline
compilation where we currently block on both.

R=ahaas@chromium.org
CC=gab@chromium.org

Bug: chromium:1101340
Change-Id: I5656697753346e5fdb15d578425cdb949ac6e364
Cq-Include-Trybots: luci.v8.try:v8_linux64_tsan_rel_ng
Cq-Include-Trybots: luci.v8.try:v8_linux64_tsan_isolates_rel_ng
Cq-Include-Trybots: luci.chromium.try:linux-rel
Cq-Include-Trybots: luci.v8.try:v8_linux_blink_rel
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2280100
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69239}