DEM injection

[changliao1025]

Previously, DEM can be injected using either (1) MPAS netcdf, and (2) a raster DEM.

Now, with the development of uraster, the injection becomes a standard alone step.
The DEM now can be injected back to (1) netcdf (2) geojson, and (3) mesh info json file.

[changliao1025]

In a global simulation, ideally all mesh cells are passed along without deduction.
And their orders remain unchanged.
Therefore, the Dem can be injected later without rearrange the arrays.