More code cleanup in disc classes.

[bartgol]

A few mods, to avoid code duplication and/or increase readability:

• create disc/extruded class for extruded disc data structures (they are, or soon will be, growing in number)
• move side set cell/node numeration maps to base class
• move creation of kokkos side-sets views from regular sideset structs to base class (can be used by all discs)
• allow recycling existing dof managers: dof managers really don't care about the fields names, so recyle an existing one if 2 dofs have the same fe type, order, dim and are on same mesh part.Must pass also the state structs (including side set ones)

[mperego]

It looks good to me.
Don't you need to modify the MpasSTKMeshStruct as well?
Thanks!

[bartgol]

It looks good to me. Don't you need to modify the MpasSTKMeshStruct as well? Thanks!

Apparently, MpasSTKMeshStruct does not override setFieldData, and just relies on the impl in GenericSTKMeshStruct.