feat: add more typed dicts to parsing

[tlambert03]

adding more typing to the parsing of raw metadata

[codecov]

Codecov Report

Merging #139 (350bdf7) into main (6943a18) will decrease coverage by 0.52%.
The diff coverage is 96.95%.

❗ Current head 350bdf7 differs from pull request most recent head 28eb743. Consider uploading reports for the commit 28eb743 to get more accurate results

@@            Coverage Diff             @@
##             main     #139      +/-   ##
==========================================
- Coverage   91.94%   91.43%   -0.52%     
==========================================
  Files          13       14       +1     
  Lines        1950     1949       -1     
==========================================
- Hits         1793     1782      -11     
- Misses        157      167      +10     

Impacted Files	Coverage Δ
src/nd2/_pysdk/_parse.py	94.24% <94.87%> (-1.44%)	⬇️
src/nd2/_pysdk/_pysdk.py	91.05% <100.00%> (-0.04%)	⬇️
src/nd2/_pysdk/_sdk_types.py	100.00% <100.00%> (ø)
src/nd2/structures.py	93.27% <100.00%> (-2.59%)	⬇️

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