Figure out what the `direction` parameter in OAVParameters means

@noemifrisina
Currently since
#2138
we interpret this as an int value instead of `ScanDirections`, since some beamlines have values other than 0 or 1, we don't know what these mean.
In theory this value should be applied to the direction PV in `setup_pin_tip_detection_params` however that is currently set to FORWARDS since we don't know how to correctly map these values.

We should figure out what the allowed values are in the oav parameters file and how to map them.

Start by tracing OAVParameters and setup_pin_tip_detection_params, especially how the direction PV currently receives FORWARDS. Check the ScanDirections handling introduced by #2138 and identify the allowed values in the OAV parameters file. Done means the beamline-specific integer values are documented and mapped correctly to the direction PV.

Written by the indexing model from the issue text.