Clean up freq_range and freq_array handling in UVCal

[bhazelton]

Description

We should really only have one of freq_array or freq_range defined on a UVCal object in the future (e.g. in version 3.0). This is along the lines of what we decided for time_range vs time_array (see #1306).

This is very clear in v 3.0+ because of the move to the wide_band structure. It's a bit muddier before that because of the support for flag arrays that have a frequency axis in delay-type calibrations.

So this PR just adds deprecation warnings for the clear cases so users can know what's coming in v3.0. To be clear:

• freq_range should not be set on non-wide-band gain style objects (which have a frequency axis)
• freq_array and channel_width should not be set on wide-band objects (which do not have a frequency axis)

It also fixes a couple of small bugs I found in testing related to handling of the freq_range parameter in the reorder_freqs and __add__ methods.

Motivation and Context

I stumbled on this while working on improvements to UVCal methods that I'm implementing as part of developing the calH5 format. I thought we should get the deprecation warnings in ASAP to give users as much heads up as possible. But I don't actually expect many users to run into this.

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.

Breaking change checklist:

• I have updated the docstrings associated with my change using the numpy docstring format.
• I have updated the tutorial to reflect my changes (if appropriate).
• My change includes backwards compatibility and deprecation warnings (if possible).
• I have added tests to cover my changes.
• All new and existing tests pass.
• I have updated the CHANGELOG.

[codecov]

Codecov Report

Merging #1361 (adb4889) into main (c643bfd) will increase coverage by 0.00%.
The diff coverage is 100.00%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1361   +/-   ##
=======================================
  Coverage   99.92%   99.92%           
=======================================
  Files          36       36           
  Lines       20230    20243   +13     
=======================================
+ Hits        20214    20227   +13     
  Misses         16       16           

Files	Coverage Δ
pyuvdata/uvcal/calfits.py	100.00% <ø> (ø)
pyuvdata/uvcal/uvcal.py	100.00% <100.00%> (ø)

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[mkolopanis]

Looks good to me. Don't normally touch the UVCal a lot but having a precedent from the time_range/time_array changes helps.