Improvement: Add test for (rather new) function t8_forest_leaf_neighbor_subface

[spenke91]

Closes #2295

Describe your changes here:

Adds a test to the function t8_forest_leaf_neighbor_subface added in #2216 .

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.36%. Comparing base (a75bc50) to head (c90e7cf).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2388      +/-   ##
==========================================
+ Coverage   82.28%   82.36%   +0.08%     
==========================================
  Files         125      125              
  Lines       20703    20709       +6     
==========================================
+ Hits        17035    17057      +22     
+ Misses       3668     3652      -16     

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[lenaploetzke]

Thanks for adding the test, i have some first comments for you :)

[spenke91]

Thanks for your review, @lenaploetzke! I incorporated your suggestions 👍

[lenaploetzke]

Very nice, nearly ready to merge.

[lenaploetzke]

Maybe also better in relation to num_neighbor_face_children?

[lenaploetzke]

Oh nice idea! Also used a similar callback in a subelement PR with n=2, we can reuse it then ;)

[lenaploetzke]

haha

Suggested change

	* \brief Set the Up test suite.
	* \brief Set up the test suite.