This allows to add additional CAs as trust anchors via the root key
"ca-trust" in the YAML config files.
Why is this helpful and can't be done for example with SRMs?
After the CA files are copied, "update-ca-trust" must be called. This
updates *all* ca trust files. This means your SRM will override all
trust files with the ones used when creating the SRM.
When you then use the SRM with a newer version of SystemRescue, you will
still use the old ca trust files from when the SRM was built.
