ENH: extend globalMeshData::calcCellCells handling

- add convenience forms for common combinations

- avoid allocation for 1:1 identity agglomerations

- support subsetting forms (avoids an intermediate fvMeshSubset)
  that also return the cellMap

- refactored to eliminate code duplication between weighted and
  unweighted forms

applications/test/checkDecomposePar/Test-checkDecomposePar.C

@@ -123,15 +123,9 @@ int main(int argc, char *argv[])
 
         const label nDomains = max(cellToProc) + 1;
 
+        // Local mesh connectivity
         CompactListList<label> cellCells;
-        globalMeshData::calcCellCells
-        (
-            mesh,
-            identity(mesh.nCells()),
-            mesh.nCells(),
-            false,
-            cellCells
-        );
+        globalMeshData::calcCellCells(mesh, cellCells);
 
         decompositionInformation info
         (