feat: support coords, find_transform, and apply_transform

[icweaver]

Features

• Pass list of (x, y) coordinates in place of img_from/img_to to bypass photometry step
• Split align_frame into a find_transform and apply_transform step

Changes to existing behavior

Only return debug data in find_transform step now instead of in align_frame. Also includes additional photometry info like psf model params.

Documentation preview: https://juliaastro.github.io/Astroalign.jl/previews/PR48/

Closes: #42, #44

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.32%. Comparing base (e445961) to head (08e9b00).

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #48      +/-   ##
==========================================
+ Coverage   99.31%   99.32%   +0.01%     
==========================================
  Files           3        3              
  Lines         145      148       +3     
==========================================
+ Hits          144      147       +3     
  Misses          1        1              

Flag	Coverage Δ
unittests	99.32% <100.00%> (+0.01%)	⬆️

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[icweaver]

Added some features based on our conversations, @RainerHeintzmann. Will eventually trim returned objects down as the initial design phase here settles, but let me know if this addresses the general behavior you requested.