worker_task: add getter for upid

sometimes we need the upid inside the worker itself, so give a
possibilty to get it

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>

src/server/worker_task.rs

@@ -589,4 +589,8 @@ impl WorkerTask {
         }
         rx
     }
+
+    pub fn upid(&self) -> &UPID {
+        &self.upid
+    }
 }