Migrate to the ophyd-async Eiger

[DominicOram]

Following DiamondLightSource/dodal#1187 we have a basic example of how to use the ophyd-async Eiger. We should add the ability to use this in Hyperion.

We will need some time for soak testing, particularly as the ophyd-async Eiger uses a different IOC, which is running on K8s. So we will need to be able to control which Eiger we use from a GDA property (e.g. a parameter in the model sent to Hyperion)

Acceptance Criteria

• There is a parameter I can send to Hyperion which makes us use the ophyd-async Eiger

[DominicOram]

We should do the XRC code first as we want to use it on i03 and on i04