Update to use new attribute API and pyright

[jsouter]

Closing #50

[codecov]

Codecov Report

Attention: Patch coverage is 73.07692% with 7 lines in your changes missing coverage. Please review.

Project coverage is 83.94%. Comparing base (3bdfc71) to head (1e4e869).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/fastcs_eiger/__main__.py	28.57%	5 Missing ⚠️
src/fastcs_eiger/eiger_controller.py	89.47%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #57      +/-   ##
==========================================
- Coverage   84.06%   83.94%   -0.13%     
==========================================
  Files           4        4              
  Lines         295      299       +4     
==========================================
+ Hits          248      251       +3     
- Misses         47       48       +1     

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[jsouter]

fastcs-eiger/src/fastcs_eiger/eiger_controller.py

Line 378 in 3f39706

match getattr(self, attr_name, None):

I'll need to fix this too

[GDYendell]

Why is this necessary if attr is AttrW?

[jsouter]

AttrW doesn't have set so pyright complains if we're trying to call set if we don't verify it's an AttrR (or I guess AttrRW).

[GDYendell]

Formatting it like this might make it look like two messages is actually one, so it is probably clearer to just do str(value) Or maybe use a different separator, like |?

I do wonder if this should be implemented in FastCS with String().validate(value).

[jsouter]

I have a feeling that in a previous release lists did automatically get cast to strings, though I may be misremembering and that was just in a dev branch I never pushed anywhere.