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/core/testing/testing.ts

@@ -49,13 +49,9 @@ export function addProviders(providers: Array<any>): void {
  *
  * @stable
  */
-export function configureModule(moduleDef: {
-  providers?: any[],
-  directives?: any[],
-  pipes?: any[],
-  precompile?: any[],
-  modules?: any[]
-}): void {
+export function configureModule(
+    moduleDef: {providers?: any[], declarations?: any[], imports?: any[], precompile?: any[]}):
+    void {
   if (!moduleDef) return;
   try {
     testBed.configureModule(moduleDef);