This change allows users to provide an optional `step_fn` callable to `StudioApp.update` and `StudioApp.update_from_viewer`. When provided, this function is called to advance the physics simulation instead of the default `step_control.advance`.
PiperOrigin-RevId: 925439890
Change-Id: Ia833503f6dd0c22fb8d75af6c5f06757496853e5
Following the export declarations in Dear ImGui and ImPlot METADATA, this change updates MuJoCo's Copybara configuration (copy.bara.sky) to export and transform the Python bindings. `//third_party/dear_imgui/google/py` exports to `python/mujoco/experimental/dear_imgui` and `//third_party/implot/google/py` exports to `python/mujoco/experimental/implot`.
PiperOrigin-RevId: 925293624
Change-Id: Ie6e32d247a6f7fc24bb36ae7060f2075d8efeb26