Add auth metadata endpoint

auth.proto

@@ -4,10 +4,13 @@ option go_package = "git.itzana.me/strafesnet/go-grpc/auth";
 
 package auth;
 
+import "google/protobuf/empty.proto";
+
 service AuthService {
   rpc GetSessionUser(IdMessage) returns (SessionUserResponse);
   rpc GetGroupRole(IdMessage) returns (RoleReponse);
   rpc ValidateSession(IdMessage) returns (ValidateResponse);
+  rpc GetAuthMetadata(google.protobuf.Empty) returns (AuthMetadataResponse);
 }
 
 message IdMessage {
@@ -32,4 +35,11 @@ message RoleItem {
 
 message ValidateResponse {
   bool Valid = 1;
-}
+}
+
+message AuthMetadataResponse {
+  string LoginURL = 1;
+  string LogoutURL = 2;
+  string AccountURL = 3;
+}
+