High-order coordinates via interpolated DMPlex (netgen-only)

[pbrubeck]

Description

• PETSc now owns the high-order coordinate PetscFE, section, and vector.
• Coordinates are inserted through oriented DMPlex closures in compiled Cython.
• Firedrake imports the distributed coordinate field into a normal coordinate Function.
• Removed physical point matching, find_permutation, netgen_distribute, sfBC_orig, and dynamic netgen_mesh/netgen_flags attributes.
• Adaptive refinement and geometric multigrid preserve high-order geometry in serial and MPI.
• Initial Netgen processing can be rank-zero-only; geometry is replicated lazily when distributed refinement needs local evaluation.

Depends on NGSolve/ngsPETSc#125

The extension to more generic high-order coordinates support via PetscFE is outlined in #5278