Feat/xarm grpc service

[jo-bru]

This PR implements the following:

• Restructuring and renaming:
  • The xarm-commander is moved to the tools directory
  • The xarm-daemon is renamed to xarm-grpc-service
  • The building process stays nearly the same
• Adding the following basic interactions/services:
  • Properties: GetVersion, GetState, SetState, SetMode, GetPosition
  • Actions: SetPosition, SetMotionEnable

The code may need some refactoring.

Resolves #37

[iomz]

Thank you!