(PUP-1218) Add ssh-ed25519 support to the sshkey type
(PUP-1218) Teach the ssh_authorized_key provider about ssh-ed25519 too.
(PUP-1218) Add spec coverage for ssh_authorized_key ssh-ed25519
(PUP-1218) Add spec coverage for sshkey ssh-ed25519
(maint) Clean up sshkey and ssh_authorizd_key type specs
Merge branch 'pull-2182'

This closes GH-2182