better error message if az_za_grid set but no az_array or za_array

[bhazelton]

Description

Give users a better error message if they set az_za_grid=True in UVBeam.interp but do not provide both the az_array and za_array.

Motivation and Context

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation change (documentation changes only)
• Version change
• Build or continuous integration change

Checklist:

• I have read the contribution guide.
• My code follows the code style of this project.

New feature checklist:

• I have added or updated the docstrings associated with my feature using the numpy docstring format.
• I have updated the tutorial to highlight my new feature (if appropriate).
• I have added tests to cover my new feature.
• All new and existing tests pass.
• I have updated the CHANGELOG.

[codecov]

Codecov Report

Merging #1302 (ef4d6c0) into main (1a84890) will increase coverage by 0.00%.
The diff coverage is 100.00%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1302   +/-   ##
=======================================
  Coverage   99.92%   99.92%           
=======================================
  Files          36       36           
  Lines       20062    20064    +2     
=======================================
+ Hits        20046    20048    +2     
  Misses         16       16           

Impacted Files	Coverage Δ
pyuvdata/uvbeam/uvbeam.py	100.00% <100.00%> (ø)

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