Test the FieldHeader getter operator

[rafacanton]

A new operator has been added to be able to get the Header of a Field as a DataTree. This PR exposes and tests its getter

[rafacanton]

This now fails as the server is not up-to-date. It passes with the right server: #2344

[github-actions]

The documentation for this pull request will be available at https://dpf.docs.pyansys.com/pull/2348. Please allow some time for the documentation to be deployed.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.11%. Comparing base (1095ea2) to head (e6a9aa7).

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2348      +/-   ##
==========================================
+ Coverage   84.10%   84.11%   +0.01%     
==========================================
  Files          91       91              
  Lines       10529    10538       +9     
==========================================
+ Hits         8855     8864       +9     
  Misses       1674     1674              

[rafacanton]

@Sangsimon Putting this work on hold so it can be more generic. I think this should fall on the Header exposure you will be working on. TODOs:

• Expose a similar operator for StringFields (I don't know why I didn't do it, all pieces are there)
• Expose the header getter here in the FieldBase class so all it children redirect the call to the appropriate op