Add include_non_enabled parameter to /subusers endpoint

- Allow listing subusers with only non-enabled grants by introducing an optional `include_non_enabled` query parameter.
- Update SQL query logic to conditionally include non-enabled subuser grants.
- Extend OpenAPI documentation to reflect the new parameter with its description and schema.

services/nginx/app/routes/subusersRoute.php

@@ -445,9 +445,17 @@ class subusersRoute
                 $response->error('Unauthorized', 401);
             }
 
+            // Optional: include_non_enabled (boolean) — when true, include subusers that only have non-enabled grants
+            $includeNonEnabled = false;
+            if (self::isParametersSet(['include_non_enabled'])) {
+                $tmp = filter_var(self::getParameter('include_non_enabled'), FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE);
+                $includeNonEnabled = $tmp === null ? false : (bool)$tmp;
+            }
+
             // Only list subusers that have an enabled grant for the caller's customer number
             $existsClause = sprintf(
-                "EXISTS (SELECT 1 FROM `subuser_grants` sg WHERE sg.`subuser` = `subusers`.`id` AND sg.`enabled` = 1 AND sg.`deleted_at` IS NULL AND sg.`billing_customer_number` = %d)",
+                "EXISTS (SELECT 1 FROM `subuser_grants` sg WHERE sg.`subuser` = `subusers`.`id` AND %ssg.`deleted_at` IS NULL AND sg.`billing_customer_number` = %d)",
+                $includeNonEnabled ? '' : 'sg.`enabled` = 1 AND ',
                 $customerNumber
             );