Test hdf5 files with flou detector

[DominicOram]

See DiamondLightSource/mx-bluesky#236

Depends on bluesky/ophyd-async#457 but also on #679

Instructions to reviewer on how to test:

1. Confirm tests pass

Checks for reviewer

• Would the PR title make sense to a scientist on a set of release notes
• If a new device has been added does it follow the standards
• If changing the API for a pre-existing device, ensure that any beamlines using this device have updated their Bluesky plans accordingly
• Have the connection tests for the relevant beamline(s) been run via dodal connect ${BEAMLINE}

[d-perl]

Closing as stale, please feel free to reopen if this is still needed