[mlir][Transform]Significantly cleanup scf.foreach_thread and GPU transform permutation handling

Previously, the need for a dense permutation leaked into the thread_dim_mapping specification.
This revision allows to use a sparse specification of the thread_dim_mapping and the proper completion / sorting is applied automatically.

In the process, the sematics of scf.foreach_thread is tightened to require a matching number of thread dimensions and mappings.
The relevant negative test is added.

Differential Revision: https://reviews.llvm.org/D137906