Tidy up editor, file tree, get list field working, allow creating new items

src/app/editor/editor.component.html

@@ -1,6 +1,8 @@
+<h2>{{ selectedMessage().name }}</h2>
 <div>
   @for (item of selectedMessage().values; track $index) {
   <app-proto-field
+    [label]="item.name"
     [configuration]="item.configuration"
     [(value)]="values()[$index]"
   ></app-proto-field>