Add include_system_workers field to ListWorkersRequest

Allows callers to opt in to seeing system workers (on temporal-sys-* task
queues) in ListWorkers responses. By default they are excluded.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: rkannan82

temporal/api/workflowservice/v1/request_response.proto

@@ -2782,6 +2782,10 @@ message ListWorkersRequest {
     //* StartTime
     //* Status
     string query = 4;
+
+    // When true, the response will include system workers (those on internal task queues
+    // like temporal-sys-*). By default, system workers are excluded.
+    bool include_system_workers = 5;
 }
 
 message ListWorkersResponse {