Murko: Move socket_handler to mx_bluesky

[DominicOram]

The socket_handler in https://github.com/DiamondLightSource/mx_auto_mjpeg_capture/tree/main/socket_handler should live in mx_bluesky so that all the code for murko interactions is in one place.

The job of the socket_handler is to:

• Listen to when image data is published to redis
• Grab the data, decode to numpy arrays
• Batch the numpy arrays
• Send results to murko
• Put the results back on a redis key
• Publish to say there are new results

Acceptance Criteria

• The socket handler code is moved into mx_bluesky
• There are tests on the above
• There is a system test where the OAVToRedis forwarder sends data to this via redis
• Docs are updated if necessary