Allows the new credential library type to be pulled from the db and used for issuing ssh certificate type credentials. The ssh cert library interfaces with vault's ssh secrets engine to either issu certificates directly from vault, or to generate them within boundary and have vault sign them as a certificate authority for authentication. See: https://developer.hashicorp.com/vault/api-docs/secret/ssh#sign-ssh-key https://developer.hashicorp.com/vault/api-docs/secret/ssh#generate-certificate-and-key
This defines a new credential library type for ssh certificates. It adds new repository methods to support CRUDL of the new ssh certificate credential library. Co-authored-by: Timothy Messier <tim.messier@gmail.com>