add some texts

Author: AhmedAbdoElhawary

lib/core/resources/strings_manager.dart

@@ -24,6 +24,10 @@ class StringsManager {
   static const String unknownPage = "Unknown page";
   static const String notInitializeGridYet = "Not initialize grid yet.";
   static const String clear = "Clear";
+  static const String clearAll = "Clear all";
+  static const String clearPath = "Clear path";
   static const String generateMaze = "Generate maze";
+  static const String searching = "Searching";
+  static const String sorting = "Sorting";
 
 }