Added ssh-keys plugin default to list

plugins/ssh-keys/functions

@@ -2,6 +2,13 @@
 set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
 source "$PLUGIN_CORE_AVAILABLE_PATH/common/functions"
 
+list_ssh_keys() {
+  declare desc="List ssh key hashes"
+  local cmd="ssh-keys:list"
+  verify_ssh_key_file
+  sshcommand list dokku
+}
+
 verify_ssh_key_file() {
   declare desc="Test that public key is valid"
   [[ -s ${DOKKU_ROOT}/.ssh/authorized_keys ]] || dokku_log_fail "No public keys found."