modern diag manager: Add more tests

[uramirez8707]

Description
This PR:

• Adds tests for the "none", "min", and "max" reduction methods (including checks for answers)
  • test_reduction_methods.F90 is the main program, it tests many different conditions
    [compute domain buffers, data_domain buffers, compute domain buffers with openmp] x [not using masks, use logical masks, use real masks] x [ subregional fields, fields with reduced k range]
  • check_time_*.F90 checks that the answers are correct
• Each reduction has its own test script (this is to take advantage of the parallelism)
• test_dm_opemp.F90 has been removed because it is already tested in test_reduction_methods.F90
• It is currently testing the old diag manager, but it be updated when the reduction methods are updated

Fixes # (issue)

How Has This Been Tested?
CI

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