all: Move the multi-configuration file reading routine to a common helper

Based on Emil's (xexaxo) feedback, we now have a common.sh file
that contains the implementation of the routine to read all config
files for kdump/pstore, and we use Makefile to join the files,
having the same implemention in all users.

Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>

module-setup.header

@@ -0,0 +1,10 @@
+#!/bin/bash
+#
+#  SPDX-License-Identifier: LGPL-2.1+
+#
+#  Copyright (c) 2021 Valve.
+#  Maintainer: Guilherme G. Piccoli <gpiccoli@igalia.com>
+#
+#  Kdump-initrd module construction/inclusion script for
+#  Dracut-based initramfs.
+#