Add a prmJointState type to match ROS Joint State message

[adeguet1]

ROS uses a single message to pass:

• position
• velocity
• effort

We should create a cisst/SAW message matching this and provide a conversion method. For the dVRK we can provide a measured joint state using the sawRobotIO class with the last encoder reading for position, compute a velocity, and report the current feedback. We can also provide a desired joint state using the info from the PID class and the computed requested current.

[adeguet1]

Done.

ROS:

• https://github.com/jhu-dvrk/dvrk-ros/commit/3da8d831ec09145d118a33ad573d2431087267d9

dVRK:

• e77f0f27df494794fb3790a1618d48f3c152d80c

PID:

• https://github.com/jhu-saw/sawControllers/commit/6ce73427c960a62a218904f30cf0787659050821
• https://github.com/jhu-saw/sawControllers/commit/b95324f080d9f5b649d2cb95e8c240dcb81cdd2f

cisst:

• https://github.com/jhu-cisst/cisst/commit/82560ad07fd7aa012362d84dac496cef6f9599b3
• https://github.com/jhu-cisst/cisst/commit/2f9de8590f4540738b0da414eab4d5ea13e01bba