OFFSPEC: add front bench

As a scientist I would like my front bench to track the beam, currently without a supermirror but in the future using one.

This is currently already in their config as a component, but no parameters or drivers have been set up:
https://control-svcs.isis.cclrc.ac.uk/git/?p=instconfigs/inst.git;a=blob;f=configurations/refl/config.py;h=7755591719e46bc6e8b715334f5ec1d92fa20c51;hb=refs/heads/NDXOFFSPEC#l134

Basic motion commissioning and testing is essential before this work starts as it's the front bench has not moved for a long time.

There will likely be a slot for doing this at the end of the March 27 cycle.

### acceptance criteria
- [ ] offspec front bench motion (two jacks and horizontal slide) are recommissioned
- [ ] reflectometry configuration is updated to add the parameters for angle,offset and seesaw
- [ ] reflectometry configuration is updated to add drivers for the two jack axes and the horizontal slide. Unlike the rear bench this does not have a Chi axis as it doesn't rotate.

Notes:
- future work will involve adding a liquid mode and also recommissioning the supermirror and adding it to the reflectometry configuration. time estimates on this are unclear.
- especially without a supermirror, the bench should follow the same max/min angles as the rear one, but it's pivot point is the supermirror Z position rather than the sample point.

Commencez par la mise en service et les tests de mouvement de base des deux jacks et de la glissière horizontale, puisque le banc avant n’a pas bougé depuis longtemps. Examinez ensuite configurations/refl/config.py et comparez la configuration du banc arrière. Le travail est considéré comme terminé lorsque les axes ont été remis en service et que la configuration de reflectometry inclut angle, offset, seesaw et les drivers pour les deux jacks et la glissière horizontale, sans axe Chi.

Rédigé par le modèle d'indexation à partir du texte de l'issue.