[AAE-622] No implicit returns (#5157)

* enable noImplicitReturns rule

* type fixes

* fix return types

* fix return value

* fix tests

* fix visibility service

* update tests

* add missing types

* fix test

lib/core/services/authentication.service.ts

@@ -163,6 +163,7 @@ export class AuthenticationService {
         if (this.alfrescoApi.getInstance()) {
             return this.alfrescoApi.getInstance().logout();
         }
+        return Promise.resolve();
     }
 
     /**