Move _check_altitude computation to core

[Yash-10]

Moving computation for check_altitude to core. Fixes #1281.

Thanks!

[codecov]

Codecov Report

Merging #1282 (7b8d7bc) into main (ea5bf1e) will increase coverage by 0.00%.
The diff coverage is 72.72%.

@@           Coverage Diff           @@
##             main    #1282   +/-   ##
=======================================
  Coverage   91.89%   91.90%           
=======================================
  Files          80       80           
  Lines        4196     4200    +4     
  Branches      360      360           
=======================================
+ Hits         3856     3860    +4     
  Misses        258      258           
  Partials       82       82           

Impacted Files	Coverage Δ
src/poliastro/core/earth_atmosphere/util.py	74.19% <62.50%> (-4.07%)	⬇️
src/poliastro/earth/atmosphere/base.py	97.22% <100.00%> (+7.22%)	⬆️

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