ENH: initial revamp of faMesh to improve modularity (#2084)

- improved separation of patch creation that is also parallel-aware,
  which now allows creation in parallel

- memory-safe use of PtrList for adding patches, with a more generalized
  faPatchData helper

- use uindirectPrimitivePatch instead of indirectPrimitivePatch
  for internal patch handling.

- align boundary methods with polyMesh equivalents

- system/faMeshDefinition instead of constant/faMesh/faMeshDefinition
  as per blockMesh convention. Easier to manage definitions, easier
  for cleanup.

- drop inheritence from GeoMesh.