McLennan OPI: Provide facility to easily load settings for different motion stages

As a scientist, support person, or developer, on the McLennan OPI, I would like the ability to easily select which motion stage is currently installed on the beamline e.g. from a drop-down box listing the ID numbers of the various rotation stages in circulation. (c.f. sample changer rack selection).

McLennan-driven motion stages, usually single axis rotation, are shared amongst the beamlines (although more often than not, stages tend to stay with particular instruments). Currently in IBEX, the drive parameter macros of the IOC need to be changed by hand if a different motion stage is installed. Obviously these need to be known either by a technician or a support person, or determined from either the macro values from where the stage was used previously, or from the configuration file used by the VI (see below).

### Acceptance Criteria

- The parameters of each stage are identified, recorded in a suitable location and format, and easily selectable from the OPI.

### Notes

There is currently an incomplete set of INI files (plain text with key-value pairs) that is used with the VI (located in `C:\LabVIEW Modules\Drivers\Mclennan PM600\INI Files`). Some are named with the ID number (e.g. ID 0017) and others with the legacy name (e.g. "Furnace Rotating Stick"). This set would be a good place to start from, depending on the solution.

Eventually the aim is to remove all mention of the legacy names and only use the ID numbers as this will avoid all confusion when discussing the stages with the various groups involved. So some work will need to be done (perhaps in a separate ticket) to discover the ID numbers of the legacy stages (if they have them) and produce settings files named accordingly.

It is recommended that _only_ the ID number of the stage be referenced anywhere on the OPI and filenames as this is the convention introduced by the SE Electronics Group and is being gradually adopted throughout ISIS. This ticket will probably need some collaboration with said group.