feat: add async_register_scanner_registration_callback and async_current_scanners to the manager

[bdraco]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 97.56098% with 1 line in your changes missing coverage. Please review.

Project coverage is 83.69%. Comparing base (ea9f985) to head (be95f13).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/habluetooth/manager.py	95.65%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #125      +/-   ##
==========================================
+ Coverage   83.27%   83.69%   +0.41%     
==========================================
  Files          12       12              
  Lines        1160     1196      +36     
  Branches      133      138       +5     
==========================================
+ Hits          966     1001      +35     
  Misses        147      147              
- Partials       47       48       +1     

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[codspeed-hq]

CodSpeed Performance Report

Merging #125 will not alter performance

_{Comparing scanner_config_sub (be95f13) with main (ea9f985)}

Summary

✅ 3 untouched benchmarks