add function to LdapInterface (#14761)

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

einterfaces/ldap.go

@@ -22,4 +22,5 @@ type LdapInterface interface {
 	GetAllGroupsPage(page int, perPage int, opts model.LdapGroupSearchOpts) ([]*model.Group, int, *model.AppError)
 	FirstLoginSync(userID, userAuthService, userAuthData, email string) *model.AppError
 	UpdateProfilePictureIfNecessary(*model.User, *model.Session)
+	GetADLdapIdFromSAMLId(authData string) string
 }