add border around editor mode dropdown container

app/assets/stylesheets/pages/repo.scss

@@ -147,7 +147,9 @@
   .dropdown {
     display: flex;
     margin-left: auto;
+    margin-bottom: 1px;
     padding: 0 $grid-size;
+    border-left: 1px solid $white-dark;
     background-color: $white-light;
 
     &.shadow {

ee/app/assets/javascripts/ide/components/editor_mode_dropdown.vue

@@ -8,7 +8,8 @@
     props: {
       hasChanges: {
         type: Boolean,
-        required: true,
+        required: false,
+        default: false,
       },
       viewer: {
         type: String,