DIAG MANAGER: Fixes to zbounds

[uramirez8707]

Description
Fixes #1879

1. Corrects the setting up starting/ending indices for sub axis to support decreasing/increasing arrays
2. Adds a select type before writing the data to correctly send subaxis data
3. Improves test by adding a test with a decreasing zaxis + adds checks to ensure the data was written correctly

How Has This Been Tested?
CI + Test case from Fabien

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules
• New check tests, if applicable, are included
• make distcheck passes