Move module-util.h to src/shared/ and load_module() to libshared

Unfortunately this needs libshared to link to libkmod. Before it was linked
into systemd-udevd, udevadm, and systemd each seperately. On most systems this
doesn't make much difference, because at least systemd would be installed, but
it might not be in small chroots. It is a small library, so I hope this is not
a big issue.

src/basic/meson.build

@@ -121,7 +121,6 @@ basic_sources = files('''
         mkdir-label.c
         mkdir.c
         mkdir.h
-        module-util.h
         mount-util.c
         mount-util.h
         nss-util.h

src/basic/module-util.h

@@ -1,10 +0,0 @@
-/* SPDX-License-Identifier: LGPL-2.1+ */
-#pragma once
-
-#include <libkmod.h>
-
-#include "macro.h"
-
-DEFINE_TRIVIAL_CLEANUP_FUNC(struct kmod_ctx*, kmod_unref);
-DEFINE_TRIVIAL_CLEANUP_FUNC(struct kmod_module*, kmod_module_unref);
-DEFINE_TRIVIAL_CLEANUP_FUNC(struct kmod_list*, kmod_module_unref_list);