feat(AppConfig): iterate how apps are managed

- auth clients are always shared, cannot be disabled
- custom connections are enabled by default, can be disabled
- any existing connections can be reconnected regardless of its AppConfig or AppAuthClient states

packages/backend/src/serializers/auth.test.js

@@ -10,6 +10,8 @@ describe('authSerializer', () => {
       fields: auth.fields,
       authenticationSteps: auth.authenticationSteps,
       reconnectionSteps: auth.reconnectionSteps,
+      sharedAuthenticationSteps: auth.sharedAuthenticationSteps,
+      sharedReconnectionSteps: auth.sharedReconnectionSteps,
     };
 
     expect(authSerializer(auth)).toStrictEqual(expectedPayload);