fix(tutorial-step): fixed interfaces

Author: nsemets

src/app/shared/models/tutorial-step.model.ts

@@ -1,13 +1,11 @@
 export interface TutorialStep {
   title: string;
   description: string;
-  position?: Position;
-  mobilePosition?: Position;
+  position: Position;
+  mobilePosition: Position;
 }
 
 interface Position {
-  top?: string;
-  left?: string;
-  right?: string;
-  bottom?: string;
+  top: string;
+  left: string;
 }