Support and abstract EPICS 7 pvAccess and pvData

[robnagler]

utils.PV.caget/put should be generally named: get/put? Perhaps this is a per-device configuration, but probably shouldn't be in the interface directly.

[nneveu]

@robnagler are you talking about this file? I think this is an example where things on the sc side were way ahead of the general device stuff. Maybe we can get rid of the pyepics folder and incorporate this in another place. @lisazacarias you wrote this and use this in some of your sc repos right? Maybe we can combine/move this to the device code area? Or is there a context where we would use this outside of interacting with devices?

[robnagler]

Yes, and there are a few other places (in bmad_modeling). Maybe channel access is necessary for now. It's use should be encapsulated so that the code doesn't have to change when channel access goes away.

[nneveu]

Yes, definitely agree we need to merge/update all places using channel access to one location to prepare for the change. I think @williamColocho 's bmad_modeling functions will be easier to update and touch less things. Bmad and utils file changes could be separate issues.