Move radio-group-images to normal ui elements (in toolbox)

It logically belongs there since it is no compound element and also 
needs to be near the other radio group.

projects/editor/src/app/unit-view/page-view/new-ui-element-panel/ui-element-toolbox.component.html

@@ -39,6 +39,11 @@
         <mat-icon>radio_button_checked</mat-icon>
         Optionsfelder
       </button>
+      <button mat-raised-button (click)="addUIElement('radio-group-images')"
+              draggable="true" (dragstart)="$event.dataTransfer?.setData('elementType','radio-group-images')">
+        <mat-icon>radio_button_checked</mat-icon>
+        Optionsfelder (Bild)
+      </button>
       <button mat-raised-button (click)="addUIElement('image')"
               draggable="true" (dragstart)="$event.dataTransfer?.setData('elementType','image')">
         <mat-icon>image</mat-icon>
@@ -60,11 +65,6 @@
     <ng-template mat-tab-label>
       <mat-icon class="example-tab-icon">widgets</mat-icon>
     </ng-template>
-    <button mat-raised-button (click)="addUIElement('radio-group-images')"
-            draggable="true" (dragstart)="$event.dataTransfer?.setData('elementType','radio-group-images')">
-      <mat-icon>radio_button_checked</mat-icon>
-      Optionsfelder (Bild)
-    </button>
     <button mat-raised-button (click)="addUIElement('likert')"
             draggable="true" (dragstart)="$event.dataTransfer?.setData('elementType','likert')">
       <mat-icon>toc</mat-icon>