HYDRAD Interface fixes

[wtbarnes]

Fix up HYDRAD interface for easier debugging.

This also reorganizes the instrument module a bit and adds two utility functions for reading and writing space-space-dimension cubes to and from xarray datasets.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 40.00000% with 30 lines in your changes missing coverage. Please review.

Project coverage is 50.87%. Comparing base (0d3bbd6) to head (bc3de92).

Files with missing lines	Patch %	Lines
synthesizAR/instruments/util.py	33.33%	16 Missing ⚠️
synthesizAR/interfaces/hydrad/hydrad.py	35.00%	13 Missing ⚠️
synthesizAR/visualize/aia.py	83.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #101      +/-   ##
==========================================
- Coverage   51.24%   50.87%   -0.38%     
==========================================
  Files          40       40              
  Lines        2092     2125      +33     
==========================================
+ Hits         1072     1081       +9     
- Misses       1020     1044      +24     

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