Merge branch 'bishtgautam/lnd/elm-moab-mesh' (PR #7575)

This adds infrastructure in ELM to use MOAB-based domain decomposition.
This is the first development step for supporting lateral connectivity across
ELM grid cells via MOAB.

[BFB]

Author: peterdschwartz

components/elm/bld/namelist_files/namelist_definition.xml

@@ -2023,7 +2023,7 @@ If TRUE setup up lateral grid connectivity in CLM.
 </entry>
 
 <entry id="domain_decomp_type" type="char*256" category="elm_initialization"
-       group="elm_inparm" valid_values="round_robin,graph_partitioning,simple" >
+       group="elm_inparm" valid_values="round_robin,graph_partitioning,simple,moab" >
 Specifies the method for decomposing CLM grids across processors.
 </entry>