Add UR Joint Torques

[MGross21]

This pull request adds new features and refactors the Universal Robots controller integration to provide access to joint torques and TCP forces, while also simplifying dependency management for the RTDE protocol. The most notable changes are the addition of methods to retrieve joint torques and TCP forces, updates to the RTDE protocol to support these features, and the removal of dynamic installation logic for the RTDE Python Client Library.

New feature additions:

• Added get_joint_torques and get_tcp_forces methods to the UniversalRobots class, allowing users to retrieve current joint torques and TCP forces from the robot.
• Extended the RTDE protocol (rtde.py) with joint_torques and tcp_force methods to provide these new data points, including version checking for joint torques support.

Protocol and configuration updates:

• Updated config.xml to include actual_current_as_torque and actual_TCP_force fields in the RTDE output recipe, enabling the retrieval of joint torques and TCP forces.
• Refactored RTDE client initialization in rtde.py to use direct imports and store the controller version for feature support checks.

Dependency management simplification:

• Removed the _check_rtde method and related dynamic installation logic from universal_robots.py, assuming the RTDE client library is pre-installed and simplifying the class initialization. [1] [2]