Add make_redshifted_cat_entry() function

[attipaci]

To complement make_redshifted_object() added earlier. A cat_entry is a much smaller footprint container, and which can be warpped into an object when needed.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.70%. Comparing base (a8e3d09) to head (b9cbbdd).
Report is 7 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #102   +/-   ##
=======================================
  Coverage   99.70%   99.70%           
=======================================
  Files           8        8           
  Lines        3055     3058    +3     
  Branches      577      577           
=======================================
+ Hits         3046     3049    +3     
  Partials        9        9           

Flag	Coverage Δ
unittests	99.70% <100.00%> (+<0.01%)	⬆️

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Files with missing lines	Coverage Δ
src/novas.c	99.62% <ø> (ø)
src/super.c	100.00% <100.00%> (ø)

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