Add missing HTG Mask checks for HTG Cell centers & Axis clip
Found by ParaView tests in the VTK bump MR, because of HTG distributed source changes: paraview/paraview!6971 (merged)
Before HTG Source changes, all processes had all trees by default. Now, the trees are on process 0 unless specified, and masked on the other processes. Some HTG filters tested in ParaView did not handle masks at all until now