Update USD dependency module paths, includes, Python imports, and plugin registration configurations across third_party/mujoco and third_party/py/mujoco from USD v23 to USD v26. PiperOrigin-RevId: 963260526 Change-Id: I3778608cb03c8903d0f545c76ae91effba3ec364
Add usd_decoder to mujoco/plugin. - Previously was src/experimental/usd/usd_to_mjspec.cc, now that same spec is returned by the plugin. PiperOrigin-RevId: 854350962 Change-Id: Ia980190a557c50ce8197980922a2594b613859b4