Add state topic containing FTS array

[alex-brinkman]

Add a state topic /fcat/state/fts that contains an array of geometry_msgs/Wrench and names of each FTS device. Similar to fcat_msgs/ActuatorStates. Since the number of FTS devices and device names are fully configurable, this interface may help realize more general downstream functions - like telemetry features and robotic behavior interfaces.

This feature would be controlled by ROS2 parameters in the same way joint_states is enabled by the create_joint_state_pub parameters. In order to keep the IPC overhead, I recommend adding a parameter to enable/disable single-topic wrench publishing.