Split out initcpio files to separate project/package
As discussed in !47 (diffs, comment 2098) we have initcpio files (in theory) only relevant to $work_dir
installed alongside the tooling.
When archiso is installed it therefore triggers a rebuild of all kernels.
It would be good to split out the initcpio files to be installable as a separate package in the archiso $work_dir
only.