Update assets. Add a-progressive-asset.

src/assets/avatars/BotDefault_Avatar.glb

src/assets/avatars/BotDefault_Avatar_Unlit.glb

src/assets/avatars/Bot_SkinnedWithAnim.glb

src/assets/environments/CliffVista_mesh.glb

src/assets/environments/MeetingSpace1_mesh.glb

src/assets/environments/OutdoorFacade_mesh.glb

src/elements/a-gltf-entity.js

src/elements/a-progressive-asset.js

src/room.html

src/room.js

src/vendor/GLTFLoader.js

webpack.config.js