Use optimal inverse transform for rectification

[oczoske]

As described in #959 , this PR implements a least-squares fit for the transformation used in rectifying spectra. This avoids the systematics caused by the interpolated inverse matrix transforms for METIS LMS. The matrix transforms can be used by setting
opttrain.rectify_cube(hdul, fit_inverse=False)

It still needs to be ensured that the PR also works for rectify_traces(), used for long-slit spectroscopy in METIS and MICADO.

[codecov]

Codecov Report

❌ Patch coverage is 9.09091% with 20 lines in your changes missing coverage. Please review.
✅ Project coverage is 75.45%. Comparing base (7a851ab) to head (2af1bb5).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
scopesim/effects/spectral_trace_list_utils.py	9.52%	19 Missing ⚠️
scopesim/effects/metis_lms_trace_list.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #961      +/-   ##
==========================================
- Coverage   75.60%   75.45%   -0.15%     
==========================================
  Files          70       70              
  Lines        8981     9001      +20     
==========================================
+ Hits         6790     6792       +2     
- Misses       2191     2209      +18     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.