Mentions: Added new endpoint, Built editor list display

app/Users/Controllers/UserSearchController.php

@@ -5,6 +5,7 @@ namespace BookStack\Users\Controllers;
 use BookStack\Http\Controller;
 use BookStack\Permissions\Permission;
 use BookStack\Users\Models\User;
+use Illuminate\Database\Eloquent\Collection;
 use Illuminate\Http\Request;
 
 class UserSearchController extends Controller
@@ -34,8 +35,43 @@ class UserSearchController extends Controller
             $query->where('name', 'like', '%' . $search . '%');
         }
 
+        /** @var Collection<User> $users */
+        $users = $query->get();
+
         return view('form.user-select-list', [
-            'users' => $query->get(),
+            'users' => $users,
+        ]);
+    }
+
+    /**
+     * Search users in the system, with the response formatted
+     * for use in a list of mentions.
+     */
+    public function forMentions(Request $request)
+    {
+        $hasPermission = !user()->isGuest() && (
+                userCan(Permission::CommentCreateAll)
+                || userCan(Permission::CommentUpdate)
+            );
+
+        if (!$hasPermission) {
+            $this->showPermissionError();
+        }
+
+        $search = $request->get('search', '');
+        $query = User::query()
+            ->orderBy('name', 'asc')
+            ->take(20);
+
+        if (!empty($search)) {
+            $query->where('name', 'like', '%' . $search . '%');
+        }
+
+        /** @var Collection<User> $users */
+        $users = $query->get();
+
+        return view('form.user-mention-list', [
+            'users' => $users,
         ]);
     }
 }