Updated generic tab styles and js to force accessible usage

Added use of more accessible tags to create tabbed-interfaces then
updated css and JS to require use of those attributes rather than custom
techniques.

Updated relevant parts of app.
Some custom parts using their own tabs though, something to improve in
future.

resources/js/components/attachments.js

@@ -45,7 +45,7 @@ export class Attachments extends Component {
         this.stopEdit();
         /** @var {Tabs} */
         const tabs = window.$components.firstOnElement(this.mainTabs, 'tabs');
-        tabs.show('items');
+        tabs.show('attachment-panel-items');
         window.$http.get(`/attachments/get/page/${this.pageId}`).then(resp => {
             this.list.innerHTML = resp.data;
             window.$components.init(this.list);