Port the recent arm64 simulator debugger improvements to arm:

  * [arm64/sim] Add a 'sim' gdb command
    https://crrev.com/c/2664448
  * [arm64/sim] Add a simple backtrace debug command
    https://crrev.com/c/2666688

Change-Id: Id58a49cfe8e643be0fb6718a0a149e2c7ea0bcaa
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2844659
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Dan Elphick <delphick@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74123}