Update the observation date modeling that has been changed during the

[lmichel]

During the MANGO REC process, it has been suggested to simplify the representation of the observation dates (mango:EpochPostion.obsDate).
The mango:ObsDate complex type has been replaced with a simple attribute where the representation is given by its dmtype (<ATTRIBUTE dmrole="mango:EpochPosition.obsDate" dmtype="year" value="2000.0" \>).

This change requires the SkyCoord builder to be updated as well as the annotation builder.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.15%. Comparing base (8316767) to head (f89b913).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #726      +/-   ##
==========================================
+ Coverage   84.10%   84.15%   +0.04%     
==========================================
  Files          79       79              
  Lines        8608     8603       -5     
==========================================
  Hits         7240     7240              
+ Misses       1368     1363       -5     

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[lmichel]

After the last comments in the MANGO data model RFC suggesting changes in the the observation date representation, this PR must be delayed until the new code support the final time representation in the model.

[bsipocz]

After the last comments in the MANGO data model RFC suggesting changes in the the observation date representation, this PR must be delayed until the new code support the final time representation in the model.

I'm changing it to a draft PR then, feel free to mark it back "ready for review" once it can be reviewed.