Revert "refactor(platform-browser): move platform-browser/animations to animations/browser (#15043)"

This reverts commit 195b863ea4.

packages/platform-browser/animations/src/animations.ts

@@ -12,4 +12,5 @@
  * Entry point for all animation APIs of the animation browser package.
  */
 export {BrowserAnimationsModule, NoopAnimationsModule} from './module';
+export {AnimationDriver} from './render/animation_driver';
 export * from './private_export';