struct aws_cryptosdk_keyring * aws_cryptosdk_raw_rsa_keyring_new(struct aws_allocator *alloc, const struct aws_string *key_namespace, const struct aws_string *key_name, const char *rsa_private_key_pem, const char *rsa_public_key_pem, enum aws_cryptosdk_rsa_padding_mode rsa_padding_mode)