Don't require type for children of subtyped resources. (#285)

internal/proto/local/controller/api/resources/authmethods/v1/auth_method.proto

@@ -39,7 +39,7 @@ message AuthMethod {
 	uint32 version = 7;
 
 	// The auth method type.  This can be "password" or "oidc".
-	string type = 8 [(custom_options.v1.generate_sdk_option) = true];
+	string type = 8;
 
 	// The attributes that are applied for the specific Auth Method type.
 	google.protobuf.Struct attributes = 9 [(custom_options.v1.generate_sdk_option) = true];