Obs name big fix

[lewisblake]

Change Summary

place obs_name as attribute in ObsEntry. set in the ObsCollection setter, not the getter. Fix tests to not use the ObsCollection getter. unrealistic.

Related issue number

N/A, see chat

Checklist

• Start with a draft-PR
• The PR title is a good summary of the changes
• PR is set to AeroTools and a tentative milestone
• Documentation reflects the changes where applicable
• Tests for the changes exist where applicable
• Tests pass locally
• Tests pass on CI
• At least 1 reviewer is selected
• Make PR ready to review

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.57%. Comparing base (8d55c2b) to head (917d2fd).
Report is 4 commits behind head on main-dev.

Additional details and impacted files

@@             Coverage Diff              @@
##           main-dev    #1427      +/-   ##
============================================
- Coverage     78.58%   78.57%   -0.01%     
============================================
  Files           137      137              
  Lines         20889    20890       +1     
============================================
  Hits          16415    16415              
- Misses         4474     4475       +1     

Flag	Coverage Δ
unittests	78.57% <100.00%> (-0.01%)	⬇️

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