Declare built-in command names inside the constructor (#5487)

This increases code consistency by placing the name in the same place where everything else about the command is defined.

src/command/defaults/WhitelistCommand.php

@@ -38,9 +38,9 @@ use const SORT_STRING;
 
 class WhitelistCommand extends VanillaCommand{
 
-	public function __construct(string $name){
+	public function __construct(){
 		parent::__construct(
-			$name,
+			"whitelist",
 			KnownTranslationFactory::pocketmine_command_whitelist_description(),
 			KnownTranslationFactory::commands_whitelist_usage()
 		);