RFC: Change SOIL_LAYER_THICKNESSES in history files to meters

[emkemp]

Currently SOIL_LAYER_THICKNESSES is set as centimeters (a legacy of the GRIB1 standard). However, recent LSMs added to LIS (NoahMP and JULES) normally use meters, and SI units are used in the GRIB2 standard.

For sanity and SI-pureness, the SOIL_LAYER_THICKNESSES should be changed to meters, and this change must be implemented (1) for all LIS LSMs; (2) for LDT; and (3) for LVT (particularly in "557 post" mode).

[emkemp]

I still think we should change all the SOIL_LAYER_THICKNESSES to SI units, for all LSMs. But this is not a high priority.