Finds the position and rotation of the `"Stand Here"` marker at trial start
find_start_position(scenario_data)The scenario data list (should be read from scenario .json file)
A list representing the position of the Stand Here marker at trial start. The list contains 6 items, `"pos_x"`, `"pos_y"`, and `"pos_z"`, the x, y, and z position of the object in Unity units (m), as well as the Euler Angles `"rot_x"`, `"rot_y"`, and `"rot_z"`. NULL if none found.