Add test build script

test_build.sh:
Add script to create dummy files for dummy releases

test_build.sh

+#!/usr/bin/env bash
+#
+# This is a dummy script to create a few files
+
+set -euo pipefail
+
+version="${1}"
+output_dir="output/test/test-${version}"
+_extension=""
+
+mkdir -pv -- "${output_dir}"
+for _extension in {efi,gz,iso,lkrn,pxe,qcow2,xz,zst}; do
+  printf "TEST FILE\n" > "${output_dir}/file.${_extension}"
+done
+
+printf 'foo{bar="baz"} 1\n' output/metrics.txt