feat: Settings write-back

[edgarrmondragon]

Why signals?

A config update may b e triggered in a number of moments during a sync (error handling, authentication, etc.). Blinker's signals would let us decouple emitting a signal at one of those moments, from processing the event in some other place.

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📚 Documentation preview 📚: https://meltano-sdk--2346.org.readthedocs.build/en/2346/

[codecov]

Codecov Report

Attention: Patch coverage is 95.83333% with 1 line in your changes missing coverage. Please review.

Project coverage is 89.23%. Comparing base (9d0c08b) to head (f098bcf).
Report is 80 commits behind head on main.

Files	Patch %	Lines
singer_sdk/plugin_base.py	94.73%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2346      +/-   ##
==========================================
+ Coverage   89.18%   89.23%   +0.05%     
==========================================
  Files          54       54              
  Lines        4788     4794       +6     
  Branches      936      936              
==========================================
+ Hits         4270     4278       +8     
+ Misses        361      359       -2     
  Partials      157      157              

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[codspeed-hq]

CodSpeed Performance Report

Merging #2346 will not alter performance

_{Comparing edgarrmondragon/feat/write-back (f098bcf) with main (9d0c08b)}

Summary

✅ 6 untouched benchmarks