Consider splitting ROS1 native functionality into its own crate

[Carter12s]

When we started I thought (hoped) that ROS1 native implementation and rosbridge implementation would share a lot more code.

As its stands they are like 99% fully independent and really only share the same codegen tools.

I think we should ultimately split ros1_native out into a crate roslibrust_ros1 and also potentially split the rosbridge functionality out into roslibrust_rosbridge the core roslibrust crate can ultimately contain a common trait based API for both implementations and re-expose the child crates with pub use statements.

As it stands if someone wants to use ros1_native functionality only, they have to pay the cost of compiling the rosbridge functionality...