BVH animation loading / retargeting (#25)

This PR adds support for BVH animation files, with a custom animation
player and retargeting solution for our Blender Rigify-based skeletal
meshes.

---------

Co-authored-by: Brooks Palin <brookspalin710@gmail.com>

studio-frontend/src/app/app.element.ts

@@ -189,7 +189,7 @@ export class AppElement extends LitElement {
 				nothing
 			}
 			<sts-viewer
-				objectId="sample-room"
+				objectId="base-human-female"
 				skyboxId="test_scene"
 				.mode=${this.mode}
 				@scene-state=${this.onSceneStateChange}