Extend submesh to higher order geometries

[jorgensd]

Current code does not actually work for higher order geometries (and does not throw an error).

This PR extends submeshes to higher order geometries (edges,facets,cell based submeshes).

[jpdean]

My assembly tests all pass with these changes

[jorgensd]

@garth-wells Can we merge this now? It has been thoroughly tested by @jpdean and adds important functionality to the class