feat: add micromanager autofocus device control autofocus

[fdrgsp]

This PR upgrades the PositionWidget and add the ability to control and use any Micromanager Autofocus device (e.g. Nikon PFS).

Linked to pymmcore-plus/useq-schema#91 and pymmcore-plus/pymmcore-plus#199.

followup to #128 and #133.

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[tlambert03]

clear

[codecov]

Codecov Report

Patch coverage: 83.44% and no project coverage change.

Comparison is base (5caef4b) 89.58% compared to head (e7fc327) 89.58%.

Additional details and impacted files

@@           Coverage Diff            @@
##             main     #147    +/-   ##
========================================
  Coverage   89.58%   89.58%            
========================================
  Files          37       38     +1     
  Lines        5029     5270   +241     
========================================
+ Hits         4505     4721   +216     
- Misses        524      549    +25     

Files Changed	Coverage Δ
src/pymmcore_widgets/_mda/_mda_widget.py	89.16% <76.92%> (-0.70%)	⬇️
...c/pymmcore_widgets/_mda/_positions_table_widget.py	86.69% <79.61%> (+0.75%)	⬆️
.../pymmcore_widgets/_mda/_autofocus_device_widget.py	93.25% <93.25%> (ø)

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