Added instrument server endpoint to check whether a multigrid controller exists

Author: tieneupin

src/murfey/instrument_server/api.py

@@ -223,6 +223,15 @@ def update_multigrid_controller_visit_end_time(
     return {"success": True}
 
 
+@router.post("/sessions/{session_id}/multigrid_controller/status")
+def check_multigrid_controller_exists(
+    session_id: MurfeySessionID,
+):
+    if controllers.get(session_id, None) is not None:
+        return {"exists": True}
+    return {"exists": False}
+
+
 class RsyncerSource(BaseModel):
     source: Path