[Fronted] Significant refactoring of mixins for containers and buttons

WTD-839
Refactoring in advance of style mods to switcher when in frame;
Cleanup of markup to remove 'icon' class from invoke-menu elements;

platform/commonUI/general/res/templates/controls/switcher.html

@@ -22,7 +22,7 @@
 <span ng-controller="ViewSwitcherController">
 
     <div
-	    class="menu-element icon-btn btn btn-menu dropdown click-invoke"
+	    class="t-view-switcher menu-element icon-btn btn btn-menu dropdown click-invoke"
 	    ng-if="view.length > 1"
 	    ng-controller="ClickAwayController as toggle"
 	    >
@@ -37,7 +37,7 @@
 	        {{ngModel.selected.glyph}}
         </span>
         <span class="name">{{ngModel.selected.name}}</span>
-        <span class='ui-symbol icon invoke-menu'>v</span>
+        <span class='ui-symbol invoke-menu'>v</span>
 
 
         <div class="menu dropdown" ng-show="toggle.isActive()">