User unique_ptr in ResourceManager

[destogl]

consider to put them in the initializer list with std::make_shared / std::make_unique.
But first, why are these shared pointer and not unique pointers, and second, why are these pointers in the first place?

Originally posted by @Karsten1987 in #147 (comment)

I started porting stuff from @Karsten1987 from #165 but it was not tivial. If someone wants to continue I uploaded this changes here: https://github.com/destogl/ros2_control/pull/new/adding_resource_storage

[destogl]

obsolete...