feat: add 'kind' field to dict output for various subclasses that are otherwise identical

[tlambert03]

allows roundtripping of to_dict for things like Shape|ManufacturerSpec|Annotation

This PR also adds a new pattern for adding validators or methods to classes without using Mixins

[codecov]

Codecov Report

Merging #185 (142021a) into main (daedfcc) will increase coverage by 0.45%.
The diff coverage is 98.68%.

@@            Coverage Diff             @@
##             main     #185      +/-   ##
==========================================
+ Coverage   96.73%   97.19%   +0.45%     
==========================================
  Files          25       24       -1     
  Lines         857      890      +33     
==========================================
+ Hits          829      865      +36     
+ Misses         28       25       -3     

Impacted Files	Coverage Δ
src/ome_types/_conversion.py	94.62% <ø> (ø)
src/ome_types/model/_shape_union.py	88.57% <0.00%> (-2.86%)	⬇️
src/ome_autogen/_config.py	100.00% <100.00%> (ø)
src/ome_autogen/_generator.py	100.00% <100.00%> (ø)
src/ome_autogen/main.py	100.00% <100.00%> (ø)
src/ome_types/__init__.py	100.00% <100.00%> (+13.33%)	⬆️
src/ome_types/_mixins/_base_type.py	98.75% <100.00%> (-1.25%)	⬇️
src/ome_types/_mixins/_kinded.py	100.00% <100.00%> (ø)
src/ome_types/_mixins/_ome.py	97.91% <100.00%> (+7.00%)	⬆️
src/ome_types/_mixins/_validators.py	100.00% <100.00%> (ø)
... and 1 more

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