Full support for ghosted/unghosted distributed triangulations

[JordiManyer]

In GridapDistributed, we generally allow the creation of ghosted/unghosted versions of objects. Although generally we require unghosted triangulations for integration, having both is usually required for more complex stuff.

The original version of the distributed code does not allow this. In fact, the code avoids doing cuts on ghosted cells. This was probably done to avoid repeating work, but it limits the potential of the distributed code. One example where the current implementation is not flexible enough is taking Skeleton/Boundary triangulations of a distributed SubFacetTriangulation, where we require access to the cuts on ghost cells in order to properly distinguish between interior and boundary faces.

In terms of performance, I would argue that creating model views to create the cuts and then mapping the cuts back to the original model is a lot more costly than doing the cuts on the ghost cells then masking out the result.
This also results is quite a lot less code, and better one-to-one comparison with what we do in GridapDistributed.

All in all, I propose changes to address all the above.