refactor: stop exporting NativeScriptModule from platform

Importing NativeScriptModule from "nativescript-angular/platform" leads to
including @angular/compiler in the bundle when doing AoT compilation
with webpack. Import from "nativescript-angular/nativescript.module"
should be used instead.

BREAKING CHANGE: User applications cannot import NativeScriptModule from
"nativescript-angular/platform" anymore.
Migration:
Before:
```
import { NativeScriptModule } from "nativescript-angular/platform";
```
After
```
import { NativeScriptModule } from
"nativescript-angular/nativescript.module";
```

Author: sis0k0

Diff for: nativescript-angular/platform.ts

@@ -33,8 +33,6 @@ import "./dom-adapter";
 import { NativeScriptElementSchemaRegistry } from "./schema-registry";
 import { FileSystemResourceLoader } from "./resource-loader";
 
-export { NativeScriptModule } from "./nativescript.module";
-
 export const NS_COMPILER_PROVIDERS = [
     COMPILER_PROVIDERS,
     {