Reflectometry: Preserve parameter autosaves for each reflectometry config

As a POLREF scientist, I would like the autosave values of reflectometry parameters (saved by the refl server to /var/refl/param.txt) to be retained when swapping between horizontal to a vertical reflectometry configs. At the moment, the text file just contains a list of key/value pairs where the key is the name of the parameter. However, parameters are named after their _relative_ movement to the tracking plane, which means the same parameter name may refer to different underlying motor axes between vertical and horizontal config (e.g. SMTRANS moves parallel to the floor in horizontal config, perpendicular to the floor in vertical config). We should ensure that these autosave values are linked to the correct parameters in the correct configuration.

As a possible solution, you could optionally pass a `name_for_autosave` argument into beamline parameters or maintain separate autosave files for each config

### Acceptance Criteria
- There is a way to link parameters to autosave values that is agnostic of the parameter name

### Note
- This is going to make testing and developing vertical mode significantly easier for POLREF