Simplify executor implementations

[jedel1043]

After seeing the avalanche of issues that our executors have, I don't think it's worth being too smart about when to exit the loop. Folks who wanna have that behaviour can just implement their own JobExecutor.

Thus, this reverts the implementation to the old behaviour of blocking when having pending timeout and interval jobs. Fortunately, run_jobs_async exists, so we can use it in our CLI to intersperse executing jobs with executing parsing and execution.

And just for good measure, it also adds a stop cancellation token to SimpleJobExecutor, in case folks still want to use it but that also want to remotely stop the event loop's execution from another thread.

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	52,963	52,963	0
Passed	49,666	49,666	0
Ignored	2,284	2,284	0
Failed	1,013	1,013	0
Panics	0	0	0
Conformance	93.77%	93.77%	0.00%

Tested main commit: 6e80e70f5f79e545d7b69d09dbb7e9263843faac
Tested PR commit: 76b32810f99dfad80545e5a783ec76fb20df968f
Compare commits: 6e80e70...76b3281

[codecov]

Codecov Report

❌ Patch coverage is 14.04959% with 104 lines in your changes missing coverage. Please review.
✅ Project coverage is 57.29%. Comparing base (6ddc2b4) to head (76b3281).
⚠️ Report is 757 commits behind head on main.

Files with missing lines	Patch %	Lines
cli/src/executor.rs	0.00%	64 Missing ⚠️
cli/src/main.rs	0.00%	35 Missing ⚠️
core/engine/src/job.rs	76.19%	5 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #4891       +/-   ##
===========================================
+ Coverage   47.24%   57.29%   +10.05%     
===========================================
  Files         476      556       +80     
  Lines       46892    60623    +13731     
===========================================
+ Hits        22154    34734    +12580     
- Misses      24738    25889     +1151     

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[nekevss]

LGTM