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

cmake/libwebp-apple-float16.patch

@@ -0,0 +1,8 @@
+diff --git a/cmake/cpu.cmake b/cmake/cpu.cmake
+--- a/cmake/cpu.cmake
++++ b/cmake/cpu.cmake
+@@ -121,3 +121,3 @@
+     # Explicitly disable SIMD.
+-    if(SIMD_DISABLE_FLAGS)
++    if(SIMD_DISABLE_FLAGS AND NOT APPLE)
+       list(GET SIMD_DISABLE_FLAGS ${I_SIMD} SIMD_COMPILE_FLAG)