net/mlx5: DR, Add modify header arg pool mechanism

Added new mechanism for handling arguments for modify-header action.
The new action "accelerated modify-header" asks for the arguments from
separated area from the pattern, this area accessed via general objects.
Handling of these object is done via the pool-manager struct.

When the new header patterns are supported, while loading the domain,
a few pools for argument creations will be created. The requests for
allocating/deallocating arg objects are done via the pool manager API.

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