Make LDAP be able to skip local 2FA (#16954)

This PR extends #16594 to allow LDAP to be able to be set to skip local 2FA too. The technique used here would be extensible to PAM and SMTP sources.

Signed-off-by: Andrew Thornton <art27@cantab.net>

services/auth/source/ldap/source_authenticate.go

@@ -97,3 +97,8 @@ func (source *Source) Authenticate(user *models.User, login, password string) (*
 
 	return user, err
 }
+
+// IsSkipLocalTwoFA returns if this source should skip local 2fa for password authentication
+func (source *Source) IsSkipLocalTwoFA() bool {
+	return source.SkipLocalTwoFA
+}