Added support to Multiplexer and Manager to terminate durable workers

[john-woolley]

I had a usecase for this in a project I'm working on and I thought it might be useful. Happy to make any changes to be more in-line with the existing codebase or planned trajectory.

[codecov]

Codecov Report

Attention: 11 lines in your changes are missing coverage. Please review.

Comparison is base (acb29c9) 88.039% compared to head (0f22249) 87.892%.

❗ Current head 0f22249 differs from pull request most recent head 062adaa. Consider uploading reports for the commit 062adaa to get more accurate results

Files	Patch %	Lines
sanic/worker/manager.py	31.250%	8 Missing and 3 partials ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #2913       +/-   ##
=============================================
- Coverage   88.039%   87.892%   -0.148%     
=============================================
  Files           94        94               
  Lines         7433      7450       +17     
  Branches      1283      1287        +4     
=============================================
+ Hits          6544      6548        +4     
- Misses         622       632       +10     
- Partials       267       270        +3     

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[john-woolley]

________________________ test_terminate_durable_worker _________________________

manager = <sanic.worker.manager.WorkerManager object at 0x7f4f58e75190>
caplog = <_pytest.logging.LogCaptureFixture object at 0x7f4f58f30910>

    def test_terminate_durable_worker(manager: WorkerManager, caplog):
        worker = manager.manage("TEST", fake_serve, kwargs={})
    
        assert "Sanic-TEST-0" in worker.worker_state
        assert len(manager.transient) == 1
        assert len(manager.durable) == 1
    
        manager.terminate_durable_worker("WRONG")
        message = "Durable worker termination failed because WRONG not found."
    
        assert "Sanic-TEST-0" in worker.worker_state
        assert len(manager.transient) == 1
        assert len(manager.durable) == 1
>       assert ("sanic.error", 40, message) in caplog.record_tuples
E       AssertionError: assert ('sanic.error', 40, 'Durable worker termination failed because WRONG not found.') in [('sanic.error', 40, 'Durable worker termination failed (None not found).')]
E        +  where [('sanic.error', 40, 'Durable worker termination failed (None not found).')] = <_pytest.logging.LogCaptureFixture object at 0x7f4f58f30910>.record_tuples

/home/runner/work/sanic/sanic/tests/worker/test_manager.py:433: AssertionError```

Closing this for now until I figure this out.

[prryplatypus]

Should be , ident; not , worker. That seems to be what's making the test fail.