feat(testing): add implicit test module

Every test now has an implicit module. It can be configured via `configureModule` (from @angular/core/testing)
to add providers, directives, pipes, ...

The compiler now has to be configured separately via `configureCompiler` (from @angular/core/testing)
to add providers or define whether to use jit.

BREAKING CHANGE:
- Application providers can no longer inject compiler internals (i.e. everything
  from `@angular/compiler). Inject `Compiler` instead. This reflects the
  changes to `bootstrap` for module support (3f55aa609f).
- Compiler providers can no longer be added via `addProviders` / `withProviders`.
  Use the new method `configureCompiler` instead.
- Platform directives / pipes need to be provided via
  `configureModule` and can no longer be provided via the
  `PLATFORM_PIPES` / `PLATFORM_DIRECTIVES` tokens.
- `setBaseTestProviders()` was renamed into `initTestEnvironment` and 
  now takes a `PlatformRef` and a factory for a
  `Compiler`.
- E.g. for the browser platform:
  
  BEFORE:
  ```
  import {setBaseTestProviders} from ‘@angular/core/testing’;
  import {TEST_BROWSER_DYNAMIC_PLATFORM_PROVIDERS,
      TEST_BROWSER_DYNAMIC_APPLICATION_PROVIDERS} from ‘@angular/platform-browser-dynamic/testing’;
  
  setBaseTestProviders(TEST_BROWSER_DYNAMIC_PLATFORM_PROVIDERS,
      TEST_BROWSER_DYNAMIC_APPLICATION_PROVIDERS);   
  ```

  AFTER:
  ```
  import {setBaseTestProviders} from ‘@angular/core/testing’;
  import {browserTestCompiler, browserDynamicTestPlatform,
      BrowserDynamicTestModule} from ‘@angular/platform-browser-dynamic/testing’;
  
  initTestEnvironment(
      browserTestCompiler,
      browserDynamicTestPlatform(),
      BrowserDynamicTestModule);

  ```
- E.g. for the server platform:
  
  BEFORE:
  ```
  import {setBaseTestProviders} from ‘@angular/core/testing’;
  import {TEST_SERVER_PLATFORM_PROVIDERS,
      TEST_SERVER_APPLICATION_PROVIDERS} from ‘@angular/platform-server/testing/server’;
  
  setBaseTestProviders(TEST_SERVER_PLATFORM_PROVIDERS,
      TEST_SERVER_APPLICATION_PROVIDERS);   
  ```

  AFTER:
  ```
  import {setBaseTestProviders} from ‘@angular/core/testing’;
  import {serverTestCompiler, serverTestPlatform,
      ServerTestModule} from ‘@angular/platform-browser-dynamic/testing’;
  
  initTestEnvironment(
      serverTestCompiler,
      serverTestPlatform(),
      ServerTestModule);

  ```

Related to #9726
Closes #9846

modules/@angular/core/testing/testing.ts

@@ -123,7 +123,7 @@ if (_global.beforeEach) {
 export function addProviders(providers: Array<any>): void {
   if (!providers) return;
   try {
-    testInjector.addProviders(providers);
+    testInjector.configureModule({providers: providers});
   } catch (e) {
     throw new Error(
         'addProviders can\'t be called after the injector has been already created for this test. ' +
@@ -132,6 +132,48 @@ export function addProviders(providers: Array<any>): void {
   }
 }
 
+/**
+ * Allows overriding default providers, directives, pipes, modules of the test injector,
+ * which are defined in test_injector.js
+ *
+ * @stable
+ */
+export function configureModule(moduleDef: {
+  providers?: any[],
+  directives?: any[],
+  pipes?: any[],
+  precompile?: any[],
+  modules?: any[]
+}): void {
+  if (!moduleDef) return;
+  try {
+    testInjector.configureModule(moduleDef);
+  } catch (e) {
+    throw new Error(
+        'configureModule can\'t be called after the injector has been already created for this test. ' +
+        'This is most likely because you\'ve already used the injector to inject a beforeEach or the ' +
+        'current `it` function.');
+  }
+}
+
+/**
+ * Allows overriding default compiler providers and settings
+ * which are defined in test_injector.js
+ *
+ * @stable
+ */
+export function configureCompiler(config: {providers?: any[], useJit?: boolean}): void {
+  if (!config) return;
+  try {
+    testInjector.configureCompiler(config);
+  } catch (e) {
+    throw new Error(
+        'configureCompiler can\'t be called after the injector has been already created for this test. ' +
+        'This is most likely because you\'ve already used the injector to inject a beforeEach or the ' +
+        'current `it` function.');
+  }
+}
+
 /**
  * @deprecated Use beforeEach(() => addProviders())
  */