Refactor based on hipscat v0.1.2

[delucchi-cmu]

Change Description

Uses the new file_io.load_parquet_to_pandas method, and test-friendly pixel list construction of a Catalog.

[codecov]

Codecov Report

Merging #117 (450d826) into main (7ae05c0) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##              main      #117   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           22        22           
  Lines          901       899    -2     
=========================================
- Hits           901       899    -2     

Files Changed	Coverage Δ
src/hipscat_import/catalog/file_readers.py	100.00% <100.00%> (ø)
...cat_import/margin_cache/margin_cache_map_reduce.py	100.00% <100.00%> (ø)
src/hipscat_import/soap/map_reduce.py	100.00% <100.00%> (ø)

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[maxwest-uw]

had one small comment about something that falls outside of the scope of this pr :) lgtm