Revert "remove unused filtered_search webpack bundle"

This reverts commit 7ed005a5.
Signed-off-by: Rémy Coutable <remy@rymai.me>

app/assets/javascripts/filtered_search/filtered_search_bundle.js

+import './dropdown_emoji';
+import './dropdown_hint';
+import './dropdown_non_user';
+import './dropdown_user';
+import './dropdown_utils';
+import './filtered_search_dropdown_manager';
+import './filtered_search_dropdown';
+import './filtered_search_manager';
+import './filtered_search_tokenizer';
+import './filtered_search_visual_tokens';

config/webpack.config.js

@@ -49,6 +49,7 @@ function generateEntries() {
 
   const manualEntries = {
     balsamiq_viewer:      './blob/balsamiq_viewer.js',
+    filtered_search:      './filtered_search/filtered_search_bundle.js',
     monitoring:           './monitoring/monitoring_bundle.js',
     mr_notes:             './mr_notes/index.js',
     notebook_viewer:      './blob/notebook_viewer.js',

spec/javascripts/test_bundle.js

@@ -125,6 +125,7 @@ if (process.env.BABEL_ENV === 'coverage') {
     './diff_notes/components/resolve_count.js',
     './dispatcher.js',
     './environments/environments_bundle.js',
+    './filtered_search/filtered_search_bundle.js',
     './graphs/graphs_bundle.js',
     './issuable/time_tracking/time_tracking_bundle.js',
     './main.js',