[Cleanup] Remove deprecated directory dune/pdelab/gridoperatorspace
[Cleanup] Remove deprecated headers left for backwards compatibility after moving constraints headers
[Cleanup] Remove deprecated per-dim and per-order FEM classes

Those classes were deprecated before the 2.0 release and have been
replaced by generic versions that are parameterized on the dimension and
the FEM order.
[TypeTree][Bugfix] Qualify access to the TMP first_type from TypeTree and include required header