Feat: clearer naming convention for init-level dicts GRIPPER_OFFSETS

[tenfoldpaper]

Currently, the package root __init__.py contains the variable GRIPPER_OFFSETS, which actually indicates the TCP offset for different grippers. Propose renaming it to GRIPPER_TCP_OFFSETS and introduce a new variable GRIPPER_MOUNT_OFFSETS to clearly differentiate between the two.
FR3DUO setup is not affected, because it was using a member variable instead of using something defined in __init__.
Went through existing files and updated existing GRIPPER_OFFSETS to the new GRIPPER_TCP_OFFSETS.

Unclear:
Existing TCP offset value for Robotiq2F85 only defines translation, not rotation (left as identity):
common.GripperType("Robotiq2F85"): common.Pose(translation=np.array([0, 0.0, 0.1493])),

Comparing Franka Hand TCP offset and mounting offset values, it seems that the TCP offset's rotation follows the mounting offset's:
TCP: common.GripperType.FrankaHand: common.Pose(pose_matrix=common.FrankaHandTCPOffset())
Mounting: common.GripperType.FrankaHand: common.Pose(rotation=common.FrankaHandTCPOffset()[:3, :3], translation=np.array([0.0, 0.0, 0.0])),
which means that Robotiq2F85's TCP offset needs to be updated (pseudocode) as:
common.GripperType("Robotiq2F85"): common.Pose(rotation=robotiq2f85_mount_rotation, translation=np.array([0, 0.0, 0.1493])),

[juelg]

shouldnt the mounting offset for the 2f85 have no rotation at all?

[tenfoldpaper]

Nope, we had this discussion during our previous project, it requires a 90 degree offset. I double-checked it with the photographs of 2f85-mounted FR3.

[tenfoldpaper]

robot-control-stack/python/rcs/envs/configs.py

Line 185 in aec9e76

gripper_mesh_quaternion_offset: ClassVar[list[float]] = [0, 0, 0.7071068, 0.7071068]

robot-control-stack/python/rcs/envs/configs.py

Line 331 in aec9e76

quaternion=np.array(self.gripper_mesh_quaternion_offset), translation=np.array([0.0, 0.0, 0.0])

This line here shows the mounting transform that was actually used for the FR3Duo setup.