add a mock grid simulation option at no_beam condition, default to be false

src/aare/common/raster_grid.py

@@ -32,6 +32,10 @@ class RasterGridRequest(BaseModel):
 
     visible: bool = True
 
+    # When True, skip all hardware and generate simulated diffraction data.
+    # The file_prefix will have "_SIMU" appended so the DB record is identifiable.
+    no_beam: bool = False
+
     def get_image_number(self) -> int:
         return self.n_x * self.n_y