Add a Valve class

[Jennefer Maldonado (jennmald)]

Not sure if this is too much of a naive approach to the fix we did at SMI with Eliot.
Adds stop function to help with valve functionality.

[Copilot]

Pull request overview

This PR introduces a new Valve device type in nslsii/devices.py, intended to support “valve functionality” by adding a stop() hook similar to the shutter behavior.

Changes:

• Adds a new Valve class inheriting from TwoButtonShutter.
• Introduces a Valve.stop() method placeholder.

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[Thomas A Caswell (tacaswell)]

By my count we have a version of this at HEX, ISS, SRX, QAS, CHX, SIX, and LIX

[Thomas A Caswell (tacaswell)]

At least at SRX we are (were?) using this for the a photon shutter, I think we need a better name.

[Jennefer Maldonado (jennmald)]

so something that captures, valves + photon shutters?

[Thomas A Caswell (tacaswell)]

The interesting property is that "does not close on stop", putting more in a normal comment.

[Thomas A Caswell (tacaswell)]

TwoButtonShutter is a bad name that I'm pretty sure I came up with live on a beamline with someone looking over my shoulder as getting this to work was the blocking issue to getting an experiment working. We think we know all of the users of this code (as far as we know it is only used on our floor) so we can be a bit aggressive with changing things.

I would propose the following names

class TwoButtonActuator:  # no stop
class TwoButtonActuatorAutoClose(TwoButtonActuator):  # the current class

class TwoButtonShutter(TwoButtonActuatorAutoClose):  # empty now, switch to warning next fall, remove next spring

[Thomas A Caswell (tacaswell)]

This now does not close despite the name.

The default stop method is a no-op so we should move the stop from the other class to this one.

[Jennefer Maldonado (jennmald)]

I am not sure if I just made it worse.