Enhancement: liquid water fraction and forcing variable names

[scrasmussen]

TYPE: enhancement

KEYWORDS: liquid water fraction, lqf, forcing variable names

SOURCE: Soren Rasmussen, NCAR

DESCRIPTION OF CHANGES:

• Liquid water fraction: if liquid water fraction is present set snowbl = (1.0 - liqfrac) * pcp, otherwise set snow to 0.
• Forcing variable names in namelist: forcing variable names T, Q, U, V, P, LW, SW can be passed to the model in the namelist.hrldas. In the namelist they take the form forcing_name_T. If the variables are not in the namelist they default to the normal hardcoded values that have been traditionally used.
• module_lsm_forcing.F transitioned to Fortran 90 interfaces

TESTS CONDUCTED: Ran Amir's liquid water fraction testcase, tested new forcing variable in namelist.hrldas, ran Croton testcase

Checklist

• Closes issue #xxxx (An issue must exist or be created to be closed. The issue describes and documents the problem and general solution, the PR describes the technical details of the solution.)
• Tests added (unit tests and/or regression/integration tests)
• Backwards compatible
• Requires new files? If so, how to generate them.
• Documentation included
• Short description in the Development section of NEWS.md

[rcabell]

Even though GitHub Actions CI testing is failing, the regression suite passes on Derecho.