Merge branch 'fs/ssh-signing-other-keytypes'

The cryptographic signing using ssh keys can specify literal keys for keytypes whose name do not begin with the "ssh-" prefix by using the "key::" prefix mechanism (e.g. "key::ecdsa-sha2-nistp256"). * fs/ssh-signing-other-keytypes: ssh signing: make sign/amend test more resilient ssh signing: support non ssh-* keytypes