fix(NcAppNavigationItem): TypeError: this.$refs.actions.$refs.menuButton is undefined

[wofferl]

☑️ Resolves

• Fix [NcAppNavigationItem] TypeError: this.$refs.actions.$refs.menuButton is undefined #6225

menuButton was renamed to triggerButton in e817174

@@ -1883,7 +1900,7 @@ export default {
                                                        disabled: this.disabled,
                                                },
                                                slot: 'trigger',
-                                               ref: 'menuButton',
+                                               ref: 'triggerButton',
                                                attrs: {
                                                        id: this.triggerRandomId,
                                                        'aria-label': this.menuName ? null : this.ariaLabel,

🏁 Checklist

• ⛑️ Tests are included or are not applicable
• 📘 Component documentation has been extended, updated or is not applicable
• 3️⃣ Backport to next requested with a Vue 3 upgrade

[ShGKme]

Thanks

[ShGKme]

Probably, we should add focus exposed method to NcActions