Page edit: Add editing of tags (#2078)

Closes #2077.

This PR adds ability to add / change / remove Tags to Pages via MainUI.
It is using existing tag-input.vue component similar as UI for Items and
Rules.

---------

Also-by: Florian Hotze <florianh_dev@icloud.com>
Signed-off-by: David Kesl <davidkesl76@gmail.com>

bundles/org.openhab.ui/web/src/components/pagedesigner/page-settings.vue

@@ -27,12 +27,22 @@
           </f7-list>
         </f7-accordion-content>
       </f7-list-item>
+      <f7-list-item accordion-item title="Tags" :disabled="page.uid === 'overview'">
+        <f7-accordion-content>
+          <tag-input :item="page" />
+        </f7-accordion-content>
+      </f7-list-item>
     </f7-list>
   </f7-col>
 </template>
 
 <script>
+import TagInput from '@/components/tags/tag-input.vue'
+
 export default {
+  components: {
+    TagInput
+  },
   props: ['page', 'createMode'],
   data () {
     return {}