Add fast_concat, generic read, and from_file methods to UVCal

[bhazelton]

Description

Adds the following methods to UVCal:

• fast_concat, similar to the one on UVData.
• read, a method that is generic across input file types.
• from_file, a class method that allows one-line UVCal object creation from a file.

Also deprecates reading multiple files in using file-specific reads (e.g. read_calfits) because the handling of combining the objects from multiple files now resides in the generic read method for less code replication and better maintainability.

Motivation and Context

closes #1169

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 #1271 (8671c7b) into main (4f873aa) will increase coverage by 0.00%.
The diff coverage is 100.00%.

Additional details and impacted files

@@           Coverage Diff            @@
##             main    #1271    +/-   ##
========================================
  Coverage   99.91%   99.91%            
========================================
  Files          33       33            
  Lines       19459    19732   +273     
========================================
+ Hits        19443    19716   +273     
  Misses         16       16            

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

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[plaplant]

Thanks @bhazelton! This is excellent and add lots of nice functionality. Just a few small questions/comments.

[plaplant]

Looks great, thanks @bhazelton!