refactor: deprecate RootRenderer / Renderer

Use `RendererV2` instead of `Renderer` now. `Renderer` can still be injected
and delegates to `RendererV2`.

Use `RendererFactoryV2` instead of `RootRenderer`. `RootRenderer` cannot be used
anymore.

BREAKING CHANGE:
- `RootRenderer` cannot be used any more, use `RendererFactoryV2` instead.
  Note: `Renderer` can still be injected/used, but is deprecated.

modules/@angular/core/test/linker/direct_rendering_integration_spec.ts

@@ -20,7 +20,8 @@ let destroyViewLogs: any[];
 export function main() {
   // Don't run on server...
   if (!getDOM().supportsDOMEvents()) return;
-  describe('direct dom integration tests', function() {
+  // TODO(tbosch): delete the tests here as they use the old renderer.
+  xdescribe('direct dom integration tests', function() {
 
     beforeEach(() => {
       directRenderer = DIRECT_DOM_RENDERER;