✨ Add rich string representation for ORM classes

[bpenteado]

For discussion: new instance representation is also applied inside of lists. Do we want that?

[github-actions]

🚀 Deployed on https://63d943743d975100744d392a--lnschema-core-yvzi.netlify.app

[codecov]

Codecov Report

Merging #95 (908a565) into main (5aab829) will decrease coverage by 2.28%.
The diff coverage is 45.45%.

❗ Current head 908a565 differs from pull request most recent head eac79e1. Consider uploading reports for the commit eac79e1 to get more accurate results

@@            Coverage Diff             @@
##             main      #95      +/-   ##
==========================================
- Coverage   87.10%   84.82%   -2.28%     
==========================================
  Files          14       14              
  Lines         380      402      +22     
==========================================
+ Hits          331      341      +10     
- Misses         49       61      +12     

Impacted Files	Coverage Δ
lnschema_core/dev/sqlmodel.py	81.64% <45.45%> (-5.86%)	⬇️

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[falexwolf]

Great! Up to small cosmetics as just discussed!

Please feel free to merge and make a release to bring it into LaminDB!