import-example: update to glimmer

Let's update the ImportExample component to extend glimmer/component
instead of ember/component. Glimmer components offer a bunch of various
advantages over classic components and are the direction that ember is
heading in general.

Author: geneukum

app/templates/components/import-example.hbs renamed to app/components/import-example.hbs

@@ -5,7 +5,7 @@
       {{#if this.showClipboardSuccessIcon}}
         {{svg-jar "success" width="24px" height="24px"}}
       {{else}}
-        <CopyButton @clipboardText={{concat "import " this.item " from '" this.package "';"}} @title="Copy to clipboard" @success={{action "showSuccess"}}>
+        <CopyButton @clipboardText={{concat "import " @item " from '" @package "';"}} @title="Copy to clipboard" @success={{this.showSuccess}}>
           {{svg-jar "copy" width="24px" height="24px"}}
         </CopyButton>
       {{/if}}
@@ -14,7 +14,7 @@
   <table class="CodeRay">
     <tbody>
       <tr>
-        <td class="code"><pre><span class="wrapper"><span class="keyword">import</span> {{item}} <span class="keyword">from</span> <span class="string">'{{this.package}}'</span>;</span></pre></td>
+        <td class="code"><pre><span class="wrapper"><span class="keyword">import</span> {{@item}} <span class="keyword">from</span> <span class="string">'{{@package}}'</span>;</span></pre></td>
       </tr>
     </tbody>
   </table>

app/components/import-example.js

@@ -1,12 +1,14 @@
-/* eslint-disable ember/classic-decorator-no-classic-methods */
 import { action } from '@ember/object';
-import Component from '@ember/component';
+import Component from '@glimmer/component';
 import { later } from '@ember/runloop';
+import { tracked } from '@glimmer/tracking';
 
 export default class ImportExample extends Component {
+  @tracked showClipboardSuccessIcon = false;
+
   @action
   showSuccess() {
-    this.toggleProperty('showClipboardSuccessIcon');
-    later(this, () => this.toggleProperty('showClipboardSuccessIcon'), 950);
+    this.showClipboardSuccessIcon = true;
+    later(this, () => (this.showClipboardSuccessIcon = false), 950);
   }
 }