Add events emitted by OverlayPanel

This PR adds the emits: ['show', 'hide'] to OverlayPanel component.
Without these vue will throw warnings in the console
Also in vue js docs, they encourage to add the emits

src/components/overlaypanel/OverlayPanel.vue

@@ -51,6 +51,7 @@ export default {
             default: null
         }
     },
+    emits: ['show', 'hide'],
     data() {
         return {
             visible: false