Re-introduce JwksValidationHandler

Just as a proof of concept, this demonstrates Implicit Flow with v9 of
the library. It pulls in the separate package for JWKS validation.

Author: jeroenheijmans

package-lock.json

@@ -18,6 +18,7 @@
     "@angular/platform-browser-dynamic": "^9.0.5",
     "@angular/router": "^9.0.5",
     "angular-oauth2-oidc": "^9.0.0",
+    "angular-oauth2-oidc-jwks": "^9.0.0",
     "core-js": "^2.6.11",
     "rxjs": "^6.5.4",
     "tslib": "^1.11.1",

package.json

@@ -1,7 +1,7 @@
 import { HttpClientModule } from '@angular/common/http';
 import { ModuleWithProviders, NgModule, Optional, SkipSelf } from '@angular/core';
-import { AuthConfig, NullValidationHandler, OAuthModule, OAuthModuleConfig, OAuthStorage, ValidationHandler } from 'angular-oauth2-oidc';
-
+import { AuthConfig, OAuthModule, OAuthModuleConfig, OAuthStorage, ValidationHandler, } from 'angular-oauth2-oidc';
+import { JwksValidationHandler } from 'angular-oauth2-oidc-jwks';
 import { authConfig } from './auth-config';
 import { AuthGuardWithForcedLogin } from './auth-guard-with-forced-login.service';
 import { AuthGuard } from './auth-guard.service';
@@ -31,7 +31,7 @@ export class CoreModule {
       providers: [
         { provide: AuthConfig, useValue: authConfig },
         { provide: OAuthModuleConfig, useValue: authModuleConfig },
-        { provide: ValidationHandler, useClass: NullValidationHandler },
+        { provide: ValidationHandler, useClass: JwksValidationHandler },
         { provide: OAuthStorage, useFactory: storageFactory },
       ]
     };