Run client callbacks in the main thread

[tpoliaw]

Still need to handle the timeout but as a proof-of-concept for testing the plotting callback it should be a start.

[codecov]

Codecov Report

❌ Patch coverage is 81.25000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 94.91%. Comparing base (162ef03) to head (f049ac9).

Files with missing lines	Patch %	Lines
src/blueapi/client/client.py	81.25%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1346      +/-   ##
==========================================
- Coverage   95.00%   94.91%   -0.10%     
==========================================
  Files          42       42              
  Lines        2765     2771       +6     
==========================================
+ Hits         2627     2630       +3     
- Misses        138      141       +3     

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