refactor(core): change module semantics

This contains major changes to the compiler, bootstrap of the platforms
and test environment initialization.

Main part of #10043
Closes #10164

BREAKING CHANGE:
- Semantics and name of `@AppModule` (now `@NgModule`) changed quite a bit.
  This is actually not breaking as `@AppModules` were not part of rc.4.
  We will have detailed docs on `@NgModule` separately.
- `coreLoadAndBootstrap` and `coreBootstrap` can't be used any more (without migration support).
  Use `bootstrapModule` / `bootstrapModuleFactory` instead.
- All Components listed in routes have to be part of the `declarations` of an NgModule.
  Either directly on the bootstrap module / lazy loaded module, or in an NgModule imported by them.

modules/@angular/platform-browser/private_export.ts

@@ -42,5 +42,6 @@ export var __platform_browser_private__ = {
   SharedStylesHost: shared_styles_host.SharedStylesHost,
   ELEMENT_PROBE_PROVIDERS: ng_proble.ELEMENT_PROBE_PROVIDERS,
   DomEventsPlugin: dom_events.DomEventsPlugin,
-  initDomAdapter: browser.initDomAdapter
+  initDomAdapter: browser.initDomAdapter,
+  INTERNAL_BROWSER_PLATFORM_PROVIDERS: browser.INTERNAL_BROWSER_PLATFORM_PROVIDERS
 };