Userland: Add support for jails

This happens in two ways:
1. LibCore now has two new methods for creating Jails and attaching
   processes to a Jail.
2. We introduce 3 new utilities - lsjails, jail-create and jails-attach,
   which list jails, create jails and attach processes to a Jail,
   respectively.

Userland/Utilities/jail-create.cpp

@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2022, Liav A. <liavalb@hotmail.co.il>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibCore/ArgsParser.h>
+#include <LibCore/System.h>
+#include <LibMain/Main.h>
+#include <unistd.h>
+
+ErrorOr<int> serenity_main(Main::Arguments arguments)
+{
+    StringView new_jail_name;
+    Core::ArgsParser args_parser;
+    args_parser.add_positional_argument(new_jail_name, "New jail name", "jail name");
+    args_parser.parse(arguments);
+
+    TRY(Core::System::pledge("stdio jail"));
+
+    if (!new_jail_name.is_null() && !new_jail_name.is_empty()) {
+        TRY(Core::System::create_jail(new_jail_name));
+        return 0;
+    }
+
+    return Error::from_string_view("Can't create a jail with empty name."sv);
+}