net/mlx5: DR, Move STEv0 modify header logic

Move HW specific modify header fields and logic to STEv0 file
and use the new STE context callbacks.
Since STEv0 and STEv1 modify actions values are different, each
version has its own implementation.

Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Reviewed-by: Alex Vesker <valex@nvidia.com>
Reviewed-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>