Use process supervisor with workers=1

[eltoder]

Summary

This enables process monitoring, so uvicorn will automatically restart the process if it dies or gets stuck, the same way as it does with multiple workers. Other features, like handling SIGHUP, SIGTTIN, SIGTTOU also work.

For cases where you don't need supervision, don't pass --workers. This is still the default.

Discussion: #2926

Checklist

• I understand that this PR may be closed in case there was no previous discussion. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.

[codspeed-hq]

Merging this PR will not alter performance

✅ 24 untouched benchmarks

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_{Comparing eltoder:feature/one-worker-manager (4effe00) with main (ad5ff87)}