Save named indices in from_dataframe

[camposandro]

Save named indices when importing data with from_dataframe. When named indices appear in data they are usually relevant and should not be dropped, at the risk of rendering the catalog useless (e.g. if they are object/source IDs).

[codecov]

Codecov Report

Attention: Patch coverage is 87.50000% with 1 line in your changes missing coverage. Please review.

Project coverage is 97.34%. Comparing base (a64e163) to head (f31d6b8).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/lsdb/loaders/dataframe/from_dataframe_utils.py	83.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #539      +/-   ##
==========================================
- Coverage   97.38%   97.34%   -0.05%     
==========================================
  Files          43       43              
  Lines        1724     1732       +8     
==========================================
+ Hits         1679     1686       +7     
- Misses         45       46       +1     

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[github-actions]

Before [a64e163]	After [b418c00]	Ratio	Benchmark (Parameter)
14.4±0.4ms	14.5±0.4ms	1.01	benchmarks.time_box_filter_on_partition
12.4±0.02s	12.6±0.02s	1.01	benchmarks.time_create_large_catalog
84.6±1ms	85.1±0.7ms	1.01	benchmarks.time_kdtree_crossmatch
1.85±0.02s	1.85±0.02s	1	benchmarks.time_create_midsize_catalog
29.2±0.3ms	28.6±0.5ms	0.98	benchmarks.time_polygon_search

Click here to view all benchmarks.