The default gltf for android's gltf-viewer is the buster drone, which uses skinning. We add an additional model (damaged helmet) as an alternative default. This will be useful for debugging WebGPU, where skinnning is not yet supported. This alternate path can only be invoke by starting the app through adb: `adb shell am start -n com.google.android.filament.gltf/.MainActivity --ez "use-static-model" true`