feat: add useq.WellPlanPlan widget with well selection

[tlambert03]

minimal working example of a plate selector extracted from @fdrgsp's code in #308

😂

TODO:

• add back well names
• support selection

[codecov]

Codecov Report

Attention: Patch coverage is 98.01980% with 4 lines in your changes missing coverage. Please review.

Project coverage is 90.54%. Comparing base (370dfcd) to head (d8f76c1).
Report is 29 commits behind head on main.

Files with missing lines	Patch %	Lines
...ymmcore_widgets/useq_widgets/_well_plate_widget.py	98.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #318      +/-   ##
==========================================
+ Coverage   90.36%   90.54%   +0.18%     
==========================================
  Files          73       74       +1     
  Lines        8135     8336     +201     
==========================================
+ Hits         7351     7548     +197     
- Misses        784      788       +4     

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[tlambert03]

all yours @fdrgsp