Page for IBEX versions on instruments

now that https://beamlog.nd.rl.ac.uk/inst_summary.xml is broken, it'd be nice to see the IBEX versions of instruments with the web dashboard instead.

the PV for this is <prefix>CS:VERSION:SVN:REV which is just a string - no dehexing or anything needed. do a caget IN:INTER::CS:VERSION:SVN:REV in an EPICS terminal to verify this if you want.

We probably don't want to link to this from any of the user-facing pages, much like the wall display.

note that the gateway on ndaextweb4 will need to be adjusted to let that PV through - see https://isiscomputinggroup.github.io/ibex_developers_manual/webdashboard/PVWS.html#gateway for information on this.