BTPS - Use Happi Devices for BtpsSourceStatus

[slactjohnson]

Current Behavior

The current BtpsSourceStatus uses PVs to create stage components. It might be useful to get these stages from the happi database rather than direct instantiation, as well as the cameras.

pcdsdevices/pcdsdevices/lasers/btps.py

Lines 661 to 669 in ce9d569

	ls1 = Cpt(
	BtpsSourceStatus,
	"LTLHN:LS1:",
	source_pos=SourcePosition.ls1,
	linear_prefix="LAS:BTS:MCS2:01:m1",
	rotary_prefix="LAS:BTS:MCS2:01:m2",
	goniometer_prefix="LAS:BTS:MCS2:01:m3",
	doc="Source status for LS1 (Bay 1)"
	)

Context / environment

We need to update some stages/cameras in the configuration. We have this information tracked in the code, rather than happi.

Suggested Solution

I'm not really sure which method is better; I just wanted to make an issue to track this idea.

[tangkong]

Having it in Happi let's us pull the device into typhos etc so there's that benefit.

It looks like the only common prefix is the first segment (LTLHN), but that's should make Happi instantiation ok