Enable MuJoCo Studio build and packaging on macos.

Also:
- Packages MuJoCo Studio as MuJoCoStudio.app in the MuJoCo.dmg.
- Fixes a Filament compile issue.
- Patches libwebp to fix compile error related to universal builds and forces
  it to build as static.
- Removes the separate, obsolete "build_studio" step.
PiperOrigin-RevId: 934564785
Change-Id: I50c83283b5e138062e37d53926a5a77fdf99dbfa

python/mujoco/experimental/studio/CMakeLists.txt

@@ -83,3 +83,26 @@ if(UNIX AND NOT APPLE)
     target_link_options(${target} PRIVATE "-Wl,--allow-multiple-definition")
   endforeach()
 endif()
+
+if(APPLE)
+  set(STUDIO_PY_MODULES
+      parser
+      native_viewer_cc
+      renderer
+      ux
+      sim
+      dear_imgui
+      implot
+  )
+  foreach(target ${STUDIO_PY_MODULES})
+    if(TARGET ${target})
+      add_custom_command(
+        TARGET ${target}
+        POST_BUILD
+        COMMAND
+          install_name_tool -add_rpath @loader_path/../../ $<TARGET_FILE:${target}>
+      )
+    endif()
+  endforeach()
+endif()
+