Check and modify output units for BMI variables in main and noah_om_grid branches

[SnowHydrology]

Some variable units were transformed to match NWM v3.0 output. However, this should not be done in the model's BMI specification as it affects how variables are passed from one model to another in a NextGen formulation.

For example, we had to revert the change to water%evapotrans so that Noah-OM would once again work when coupled to CFE and TOPMODEL: #115

This issue is to check the BMI implementation of the main and noah_om_grid branches to ensure variable units are correct and that no transforms are performed in get_value.

See example here of the variable ECAN, which needs to be fixed:

noah-owp-modular/bmi/bmi_noahowp.f90

Line 942 in 37d8d82

case("ECAN")

For each variable, the developer must update:

• the variable description and units in output_items
• the units in noahowp_var_units
• the dest value in noahowp_get_float
• the variable equation in noahowp_set_float