Introduce an inspector client interface method for running an
"instrumentation pause" (when an instrumentation breakpoint is hit).
This allows the client to run a more restrictive version of message
pumping on instrumentation breakpoint hits.

If not overriden, the instrumentation pause message loop handler will
run the normal message loop. Such an implementation preserves the
behavior for existing clients.

Bug: chromium:1354043
Change-Id: Id33bb10503d73b59b24e63fd9d24631611f68dee
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3863256Reviewed-by: Kim-Anh Tran <kimanh@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82881}