Rename popover classes

Part of an update to align the naming schemes across our components.

- Renames .popover-title to .popover-header
- Renames .popover-content to .popover-body

Refs: #22092

js/dist/popover.js

@@ -35,7 +35,7 @@ var Popover = function ($) {
     placement: 'right',
     trigger: 'click',
     content: '',
-    template: '<div class="popover" role="tooltip">' + '<div class="arrow"></div>' + '<h3 class="popover-title"></h3>' + '<div class="popover-content"></div></div>'
+    template: '<div class="popover" role="tooltip">' + '<div class="arrow"></div>' + '<h3 class="popover-header"></h3>' + '<div class="popover-body"></div></div>'
   });
 
   var DefaultType = $.extend({}, Tooltip.DefaultType, {
@@ -48,8 +48,8 @@ var Popover = function ($) {
   };
 
   var Selector = {
-    TITLE: '.popover-title',
-    CONTENT: '.popover-content'
+    TITLE: '.popover-header',
+    CONTENT: '.popover-body'
   };
 
   var Event = {