MAINT: backwards compatibility utils for PV name change

[ZLLentz]

• PV name needed to change because it was too long (limit 60 chars)
• Some IOCs are updated, some are not
• I want the ui to work regardless, so let's make both versions work

This ended up having some cascading buggy behavior. The best way to resolve this was to refactor and clean up a lot of the eV range handling, doing it via widget promotion instead of by ad-hoc function applications.

Later, I was asked to make some adjustments to the beamclass table in the PMPS WG meeting e.g. citing the source and adding table header tooltips.

[ZLLentz]

This is currently live but doesn't immediately need to be merged

[ZLLentz]

I've updated the homs xrt prefixes as described in https://github.com/pcdshub/lcls-plc-xrt-optics/pull/48 but have not updated the live folder yet because the old PVs are still up

[ZLLentz]

I'm a bit tired of keeping this open, I'm going to merge it. There shouldn't be anything controversial in here and I want to run off of master instead of my fork for the upcoming experiment cycle.