add camera frame id to camera info message

Hi, I found a problem with the camera info message. According to the documentation of the camera info manager, "the time stamp and frame_id should normally be the same as the corresponding Image message Header fields." The caller of the getCameraInfo method is responsible for filling in these fields (see camera_info_manager.cpp).

Currently, only the timestamp is set the same. This is why I added the respective line for the frame_id.

Best regards, Martin