Add lease duration to worker heartbeat request

Author: rkannan82

temporal/api/workflowservice/v1/request_response.proto

@@ -2467,6 +2467,11 @@ message RecordWorkerHeartbeatRequest {
     string identity = 2;
 
     repeated temporal.api.worker.v1.WorkerHeartbeat worker_heartbeat = 3;
+
+    // Duration for which the worker lease should be valid.
+    // Server will calculate the actual expiration time based on when it receives this request.
+    // If not specified or zero, the server will use a default lease duration (typically 60 seconds).
+    google.protobuf.Duration lease_duration = 4;
 }
 
 message RecordWorkerHeartbeatResponse {