SimpleCommandMap: Enforce command permissions by default (#4681)

this resolves many security issues, as well as removing a ton of boilerplate code.
It may be desirable to react to permission denied; this can be done by overriding Command->testPermission(), or by using setPermissionMessage() to set a custom permission denied message.

src/command/defaults/KillCommand.php

@@ -47,10 +47,6 @@ class KillCommand extends VanillaCommand{
 	}
 
 	public function execute(CommandSender $sender, string $commandLabel, array $args){
-		if(!$this->testPermission($sender)){
-			return true;
-		}
-
 		if(count($args) >= 2){
 			throw new InvalidCommandSyntaxException();
 		}