Bugfix in the calculations of immediate melting and supersaturation dynamical tendenc...

Bugfix in the calculations of immediate melting and supersaturation dynamical tendency (#1925)

TYPE: bug fix

KEYWORDS: Melting, Supersaturation

SOURCE: Jacob Shpund (Pacific Northwest National Lab),
Kangen Huang (Nanjing University)
Alexander Khain (The Hebrew University of Jerusalem)

DESCRIPTION OF CHANGES:
Problem:
This PR addresses the following problems: (1) The order of accumulating the melted mass was erroneous and based on the hydrometeor state after melting. (2) Changes in temperature and water vapor after advection were used via low-order approximation for calculating the supersaturation that caused relatively high values of total mass imbalance. (3) Corresponding code cleanup.

Solution:
(1) Changing the order in melting
(2) Calculating the dynamical tendency directly from the perturbation of Temperature and water vapor

LIST OF MODIFIED FILES:
WRF/phys/module_mp_fast_sbm.F

TESTS CONDUCTED:
1. The code compiles (Intel OneAPI 2021.1.1)
2. The melting correction has a very small affect on deep convective cloud state
3. The supersaturation dynamical tendency can cause evident changes in cloud depth of shallow clouds with local (transient) forcing. Otherwise, this fix improves the accuracy of the total mass balance.
4. The regression tests are all passing.

RELEASE NOTE: Fixed the calculation order in the immediate melting, and the calculation method in the supersaturation dynamical tendency.