feat: add interface for returning reports from function classes passed to from_map

[douglasdavis]

This supersedes #415

High level overview: dask-awkward's from_map function takes a callable as the first argument (func). If that callable has a return_report property that returns True, then from_map will return two collections. The first will be the Array collection of interest (computes to be the intended data array) and the second will be another Array collection that computes to some user defined thing implemented for the specific func that gets passed into from_map.

[codecov-commenter]

Codecov Report

Attention: 4 lines in your changes are missing coverage. Please review.

Comparison is base (2ce95fa) 92.96% compared to head (d64f8a5) 93.06%.

Files	Patch %	Lines
src/dask_awkward/lib/io/parquet.py	88.88%	3 Missing ⚠️
src/dask_awkward/lib/io/columnar.py	83.33%	1 Missing ⚠️

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #433      +/-   ##
==========================================
+ Coverage   92.96%   93.06%   +0.10%     
==========================================
  Files          23       23              
  Lines        3197     3245      +48     
==========================================
+ Hits         2972     3020      +48     
  Misses        225      225              

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