feat: Bridge twist message to set_velocity API for high level movement

[MiaoDX]

Hi, thanks for the ROS2 wrapper.

It maybe helpful it we can support twist message directly.

And my limited testing show that our current BaseClient can be not so suitable for calling multi times.

With all the changes:

---

Testing:

# In terminal 1, launch the bridge
./install/unitree_ros2_example/bin/g1_twist_bridge --ros-args -p velocity_duration:=0.5 -p velocity_update_period_ms:=200

# In terminal 2, give the twist msg
ros2 topic pub /cmd_vel geometry_msgs/msg/Twist "{linear: {x: 0.15, y: 0.0}, angular: {z: 0.0}}" -r 5
# Ctrl-C to stop move

Sincerely,
MiaoDX