[MLIR][OpenMP] Add canonical loop operations (#147061)
Add the supporting OpenMP Dialect operations, types, and interfaces for
modelling
MLIR Operations:
* omp.newcli
* omp.canonical_loop
MLIR Types:
* !omp.cli
MLIR Interfaces:
* LoopTransformationInterface
As a first loop transformations to be able to use these new operation in
follow-up PRs (#144785)
* omp.unroll_heuristic
