Add surface integration feature

[gthyagi]

No description provided.

[julesghub]

knepley's comment for this feature
Can you use https://petsc.org/main/manualpages/DMPlex/DMPlexComputeBdIntegral/ ?

[lmoresi]

I think that would work - we probably need to wrap it as we did with the volume integrals.

We could also fake it with an approximate delta function at the surface (we did this before for boundary conditions). That would be a workaround until the wrapper is implemented.

[gthyagi]

I will try the suggestions

[lmoresi]

@jcgraciosa - can we assign this to you ?

[jcgraciosa]

@lmoresi yes, please do.