Initial discord remote auth support.

It works, but nothing is persisted yet as the user object needs some tweaking
especially the database side.

remoteauth/user.go

@@ -0,0 +1,29 @@
+package remoteauth
+
+import (
+	"fmt"
+	"strings"
+)
+
+type User struct {
+	UserID        string
+	Discriminator string
+	AvatarHash    string
+	Username      string
+
+	Token string
+}
+
+func (u *User) update(payload string) error {
+	parts := strings.Split(payload, ":")
+	if len(parts) != 4 {
+		return fmt.Errorf("expected 4 parts but got %d", len(parts))
+	}
+
+	u.UserID = parts[0]
+	u.Discriminator = parts[1]
+	u.AvatarHash = parts[2]
+	u.Username = parts[3]
+
+	return nil
+}