We need to have a key that can be used to sign kernel modules and specifically 3rd party kernel modules. Add support for creating this key in abuild-keygen. ref: https://gitlab.alpinelinux.org/alpine/aports/-/issues/14873
use a fake openssl for abuild-keykey and pre-generate the abuild keys. This makes tests run significantly faster as we dont need to generate new keys for each abuild-keygen test.