Implement restart ordering

[ahopkins]

Replaces #2623
Closes #2619

Current logic terminates a process (sends SIGINT), then starts a new process.

This PR makes the following changes/additions:

• Adds functionality to reverse the order so that a worker must ack before terminating the old process
• Moves the ack to after before_server_start

[codecov]

Codecov Report

Base: 88.555% // Head: 88.571% // Increases project coverage by +0.015% 🎉

Coverage data is based on head (bd9fc5d) compared to base (518152d).
Patch coverage: 98.780% of modified lines in pull request are covered.

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #2632       +/-   ##
=============================================
+ Coverage   88.555%   88.571%   +0.015%     
=============================================
  Files           81        82        +1     
  Lines         6702      6746       +44     
  Branches      1143      1152        +9     
=============================================
+ Hits          5935      5975       +40     
- Misses         528       530        +2     
- Partials       239       241        +2     

Impacted Files	Coverage Δ
sanic/mixins/signals.py	96.551% <ø> (ø)
sanic/worker/process.py	90.909% <97.222%> (+2.020%)	⬆️
sanic/app.py	89.836% <100.000%> (+0.018%)	⬆️
sanic/constants.py	100.000% <100.000%> (ø)
sanic/mixins/startup.py	91.196% <100.000%> (ø)
sanic/server/runners.py	89.156% <100.000%> (+0.132%)	⬆️
sanic/worker/constants.py	100.000% <100.000%> (ø)
sanic/worker/inspector.py	94.047% <100.000%> (+0.145%)	⬆️
sanic/worker/manager.py	91.071% <100.000%> (+0.565%)	⬆️
sanic/worker/multiplexer.py	100.000% <100.000%> (ø)
... and 1 more

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