[Fixed Position] Add 'Add' menu button

Add UI for the Add button in fixed position view,
WTD-880.

platform/forms/res/templates/controls/menu-button.html

@@ -0,0 +1,27 @@
+<div class="s-btn s-icon-btn s-very-subtle btn-menu menu-element dropdown click-invoke"
+     ng-controller="ClickAwayController as toggle">
+
+    <span ng-click="toggle.toggle()">
+        <span class="ui-symbol icon">{{structure.glyph}}</span>
+        <span class="title-label" ng-if="structure.text">
+            {{structure.text}}
+        </span>
+        <span class='ui-symbol icon invoke-menu'
+              ng-if="!structure.text">
+            v
+        </span>
+    </span>
+
+    <div class="menu dropdown" ng-show="toggle.isActive()">
+        <ul>
+            <li ng-repeat="option in structure.options">
+                <a href="" ng-click="structure.click(option.key); toggle.setState(false)">
+                    <span class="ui-symbol type-icon icon">
+                        {{option.glyph}}
+                    </span>
+                    {{option.name}}
+                </a>
+            </li>
+        </ul>
+    </div>
+</div>