LibCore+LibGUI: Define a Serenity version in LibCore

Before, `AboutDialog` and `ArgsParser` read from a build-time created
file called `/res/version.ini`. This caused problems with utilities
unveiling specific paths leaving the version file unaccessible.

This commit hard-codes a serenity version in `LibCore`, and use it in
`ArgsParser` and `AboutDialog`.

The previous version contained the hash of the last GIT commit, this is
omitted for the default use for the sake of simplicity.

Userland/Libraries/LibCore/Version.h

@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2021, Mahmoud Mandour <ma.mandourr@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/StringView.h>
+
+namespace Core::Version {
+
+constexpr StringView SERENITY_VERSION = "Version 1.0"sv;
+
+}