Previously, we recorded pairs of (bytecode offset, sparkplug pc) to
create a mapping of bytecode offset <-> sparkplug pc.
These pairs were only recorded after builtin/runtime calls.
In preparation for deoptimizing to Sparkplug, we need a more precise
mapping.
With this CL, we record positions for every bytecode. Instead of storing
a pair of (bytecode offset, sparkplug pc), we store only the pc,
calculating the bytecode offset from the index in the mapping table.
For easier use an iterator to access the mapping is introduced.

Drive-by: Reduce sampling interval in cpu-profiler cctest to get rid of
flaky failures.

Bug: v8:11420, v8:11429
Change-Id: I36a9171f43a574eb67880cbca6cf9ff7ab291e60
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2720189Reviewed-by: Victor Gomes <victorgomes@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Auto-Submit: Patrick Thier <pthier@chromium.org>
Commit-Queue: Patrick Thier <pthier@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73186}