Add checkbox based multiselect util component

Takes an array of objects (name, checked, description) and turns it into
a list of checkboxes, one for each element

frontend-reactive/tests/integration/components/util/multiselect-test.ts

@@ -0,0 +1,26 @@
+import { module, test } from 'qunit';
+import { setupRenderingTest } from 'frontend-reactive/tests/helpers';
+import { render } from '@ember/test-helpers';
+import { hbs } from 'ember-cli-htmlbars';
+
+module('Integration | Component | util/multiselect', 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`<Util::Multiselect />`);
+
+    assert.dom().hasText('');
+
+    // Template block usage:
+    await render(hbs`
+      <Util::Multiselect>
+        template block text
+      </Util::Multiselect>
+    `);
+
+    assert.dom().hasText('template block text');
+  });
+});