Create a filter wheel attenuator device

[noemifrisina]

Some beamlines, eg I24 and soon I19, have filter wheels on their attenuators, for which there is not yet a device

Acceptance Criteria

• There is a fairly general filter wheel device with common features that beamline-specific attenuators can use

[DiamondJoseph]

Is the implementation anything similar to p99's FilterMotor, with an enum of possible positions?

[olliesilvester]

Also needed for VMXM's attenuator device. In fact, I think vmxm and i24 have almost the same EPICS attenuator - just a different number of filters. I will pick this up

[olliesilvester]

Is the implementation anything similar to p99's FilterMotor, with an enum of possible positions?

Yes, same thing here - but the enum options are different