add LocalSubhaloID and SubhaloID field

[cbyrohl]

For Arepo snapshots with FoF+Subfind data, introduce more mapped per-particle fields.

[codecov]

Codecov Report

Patch coverage: 53.84% and project coverage change: +0.75% 🎉

Comparison is base (206ad97) 56.08% compared to head (de89d15) 56.84%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #71      +/-   ##
==========================================
+ Coverage   56.08%   56.84%   +0.75%     
==========================================
  Files          53       53              
  Lines        4711     4729      +18     
  Branches      938      942       +4     
==========================================
+ Hits         2642     2688      +46     
+ Misses       1870     1839      -31     
- Partials      199      202       +3     

Files Changed	Coverage Δ
tests/test_fields.py	25.97% <0.00%> (ø)
src/scida/customs/arepo/dataset.py	35.12% <56.00%> (+2.00%)	⬆️

... and 6 files with indirect coverage changes

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.