This fixes an issue where Fedora-38 hosts can not build CentOS-Stream-9
images due to an incompatible gpg key with the new default settings for
rpm.
On Fedora-38, rpm has changed to use a new backend for key verification
and by default does not support SHA1 anymore, although the support for
SHA1 can be re-enabled via a config file. The (current) CentOS-Stream-9
keys however still require SHA1 support in order to be importable. So
they are now unusable on Fedora-38 unless SHA1 support is re-enabled.
In OSBuild, the initial chroot does not contain the config files and so
SHA1 support is disabled when rpmkeys from the host is called. It does
not matter if the crypto-policies on the host machine is configured with
the exception to support SHA1 because the chroot filters that out. This
means it may not be possible to assemble CentOS-Stream-9 based images
without disabling the key check.
This patch adds an explicit conditional case for Fedora-38 to inject the
needed configuration file into /etc/crypto-policies/back-ends to enable
SHA1 support for rpm by default. It does this by copying the default
policies from /usr/share/crypto-policies. The result is OSBuild behaving
similar to the previous behaviour seen on Fedora-37 and earlier.
Now that we can automatically detect the best available runner for
a requested one, we don't need to maintain the link farm with the
explicit mapping anymore.
