Issue 170 align spectrum along trace

[hpparvi]

This PR addresses Issue #170 by introducing a utility function specreduce.utils.align_2d_spectrum_along_trace to align a rectilinear 2D spectrum image along a trace. The function is based on the specreduce.extract._align_along_trace function and adds (optional) sub-pixel precision shifting using linear interpolation, mask handling, and uncertainty propagation (when using the 'interpolate' method). I can change the specreduce.extract code to use the new function after @cshanahan1's masking code (PR #216) has been merged.

[codecov]

Codecov Report

Attention: Patch coverage is 83.33333% with 10 lines in your changes missing coverage. Please review.

Project coverage is 83.30%. Comparing base (140e817) to head (476f865).

Files with missing lines	Patch %	Lines
specreduce/utils/utils.py	83.33%	10 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #235      +/-   ##
==========================================
- Coverage   83.33%   83.30%   -0.03%     
==========================================
  Files          13       13              
  Lines        1140     1198      +58     
==========================================
+ Hits          950      998      +48     
- Misses        190      200      +10     

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