[OOBE][QuickStart] Add QuickStart debugger

Add the frontend files that are used by the QuickStart debugger into the
codebase and add the command line switch to enable it.

Bug: b:283825193
Change-Id: Ib41c873fd204ad222a0164a71f29172f973e1ddc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4552658


Reviewed-by: Danila Kuzmin <dkuzmin@google.com>
Commit-Queue: Renato Silva <rrsilva@google.com>
Cr-Commit-Position: refs/heads/main@{#1147539}