feat: Add empty copy-button component to ui/core

ui/core/app/components/copy-button/index.hbs

@@ -0,0 +1 @@
+{{yield}}

ui/core/app/components/copy-button/index.js

@@ -0,0 +1,4 @@
+import Component from '@glimmer/component';
+
+export default class CopyButtonComponent extends Component {
+}

ui/core/tests/integration/components/copy-button-test.js

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+import { module, test } from 'qunit';
+import { setupRenderingTest } from 'ember-qunit';
+import { render } from '@ember/test-helpers';
+import { hbs } from 'ember-cli-htmlbars';
+
+module('Integration | Component | copy-button', function(hooks) {
+  setupRenderingTest(hooks);
+
+  test('it renders', async function(assert) {
+    // Set any properties with this.set('myProperty', 'value');
+    // Handle any actions with this.set('myAction', function(val) { ... });
+
+    await render(hbs`<CopyButton />`);
+
+    assert.equal(this.element.textContent.trim(), '');
+
+    // Template block usage:
+    await render(hbs`
+      <CopyButton>
+        template block text
+      </CopyButton>
+    `);
+
+    assert.equal(this.element.textContent.trim(), 'template block text');
+  });
+});