to use the [SpiderMonkey Debugger
API](https://firefox-source-docs.mozilla.org/js/Debugger/), we need to
call it from an internal debugger script that we will supply. this
script must run in the same runtime as the debuggee(s), but in a
separate
[compartment](https://udn.realityripple.com/docs/Mozilla/Projects/SpiderMonkey/Compartments)
([more
details](https://hacks.mozilla.org/2020/03/future-proofing-firefoxs-javascript-debugger-implementation/)).
this patch defines a new DebuggerGlobalScope type and a new debugger
script resource. when creating each script thread, we create a debugger
global, load the debugger script from resources/debugger.js, and run
that script in the global to initialise the Debugger API.
subsequent patches will use the debugger script as an RPC mechanism for
the Debugger API.
Testing: no testable effects yet, but will be used in #37667
Fixes: part of #36027
---------
Signed-off-by: Delan Azabani <dazabani@igalia.com>
Co-authored-by: atbrakhi <atbrakhi@igalia.com>
