Feature/pst mwsurfem

[StegmannJCSDA]

Description

This PR adds a new unit test test_MWSurfEM that tests the CRTM_SfcOptics, ONLY: CRTM_Compute_SfcOptics function for all 22 channels of atms_npp.
The test is a preliminary for future MW surface emissivity code changes.

Output:

• The unit test is successful if Error_Status==SUCCESS is asserted for all included function calls, most importantly for CRTM_Compute_SfcOptics.
• The test prints one SfcOptics%Emissivity for each ChannelIndex.

Issue(s) addressed

Resolves StegmannJCSDA#1.

Dependencies

• Requires atms_npp SpcCoeff coefficients in test data.

Impact

Expected impact on downstream repositories:

• One additional unit test for all repositories that call CRTMv3 unit tests during their build process.
• Increased test time: ca. +0.3 sec.

Checklist

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have run the unit tests before creating the PR

[chengdang]

This PR looking great. All unit tests passed with gfortran.

[chengdang]

Question: any particular reason to replace this with atms_n21?