Check variable type intents in main and noah_om_grid branches

[SnowHydrology]

Similar to the issue observed in Snow-17 (NOAA-OWP/snow17#37), incorrect intents can give rise to errors in some compilers:

#116 (comment)

This issue is to check the intents in the subroutines of the Noah-OM variable types in both the main and noah_om_grid branches.

Also, research beforehand the pros and cons of not defining the intent (some of the types do not declare intents (e.g.,

noah-owp-modular/src/WaterType.f90

Line 96 in 37d8d82

class(water_type) :: this

).