MM-23244: Validate that AuthData and AuthService fields are mutually inclusive. (#14175)

* MM-23244: Validate that either both or neither AuthData and AuthService fields are set.

* MM-23244: Readability improvement.

* MM-23244: Adds translation. Tests for error id.

* MM-23244: Fix test.

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

app/import_validators.go

@@ -219,6 +219,17 @@ func validateUserImportData(data *UserImportData) *model.AppError {
 		return model.NewAppError("BulkImport", "app.import.validate_user_import_data.auth_data_length.error", nil, "", http.StatusBadRequest)
 	}
 
+	blank := func(str *string) bool {
+		if str == nil {
+			return true
+		}
+		return len(*str) == 0
+	}
+
+	if (!blank(data.AuthService) && blank(data.AuthData)) || (blank(data.AuthService) && !blank(data.AuthData)) {
+		return model.NewAppError("BulkImport", "app.import.validate_user_import_data.auth_data_and_service_dependency.error", nil, "", http.StatusBadRequest)
+	}
+
 	if data.Password != nil && len(*data.Password) == 0 {
 		return model.NewAppError("BulkImport", "app.import.validate_user_import_data.password_length.error", nil, "", http.StatusBadRequest)
 	}