allow matched pixels/wavelengths to be in either direction

[cshanahan1]

This PR removes sorting in wavelength calibration to allow for either right-to-left or left-to-right inputs. A check that input matched pixels/wavelengths are monotonic in either direction is added.

Addresses #174

[codecov[bot]]

Codecov Report

Merging #177 (b6c792f) into main (014f37b) will increase coverage by 0.06%. The diff coverage is 85.71%.

@@            Coverage Diff             @@
##             main     #177      +/-   ##
==========================================
+ Coverage   81.28%   81.35%   +0.06%     
==========================================
  Files          10       10              
  Lines         983      992       +9     
==========================================
+ Hits          799      807       +8     
- Misses        184      185       +1     

Impacted Files	Coverage Δ
specreduce/wavelength_calibration.py	87.39% <85.71%> (+0.12%)	:arrow_up:

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[kecnry]

Can we remove the internal sorting with this check in place? Is there anything fundamental in the logic that would prevent us from handling the inverted case (besides the internal sorting - if the check was instead to make sure that they either increase or decrease, would that work)?

[cshanahan1]

thanks everyone, im going to merge this now :)