ArduPilot Backend Support

[TomerTip]

Added support for ArduPilot-Copter backend - bridging between the ArduPilot project and IsaacSim, allowing the ArduPilot community to leverage IsaacSim's physics simulation and photorealistic rendering capabilities!
You can take a look at the forked repo PegasusArduPilot

1. Had changes in the Backend and BackendConfig classes hierarchy - making the code more extendable and less couples with PX4
   

2. Added backend selection UI that allows the user to choose a backend and its settings before spawning the vehicle.
   

3. Launching ArduPilot-SITL on play button and and shutting down on stop button.
   

4. Implementend the communication module PyArduPilotPlugin in order to allow communication between the simulator and ArduPilot SITL - enabling a control loop of sensor data and motor commands.