feat(search): create search plugin extension

Signed-off-by: Camila Belo <camilaibs@gmail.com>

plugins/search/src/alpha.tsx

@@ -51,6 +51,7 @@ import {
 } from '@backstage/core-plugin-api';
 
 import {
+  createPlugin,
   createApiExtension,
   createPageExtension,
   createExtensionInput,
@@ -487,3 +488,9 @@ export const SearchNavItem = createNavItemExtension({
     ),
   },
 });
+
+/** @alpha */
+export default createPlugin({
+  id: 'plugin.search',
+  extensions: [SearchApi, SearchPage, SearchModal, SearchNavItem],
+});