Updated StandardAxisCam to use software trigger mode

[thopkins32]

Summary

This enables the use of software triggering mode for the StandaradAxisCam.

How it works

Quick note: I use the term arm/disarm below to mean that we are starting/stopping capturing. I am not sure if my use of this word is correct in this context.

• When staging: Change trigger mode to "Software" and start capturing (effectively arming the detector).
• When triggering: Send one acquisition signal (acquire one or many frames in multiple image mode).
• When unstaging: Stop capturing (effectively disarming the detector).

Example

RE(count([axis_standard], num=5))

This triggers an acquisition 5 separate times. Currently, this arms and disarms the detector 5 times, one for each trigger. After this change, it will only arm and disarm once, during stage and unstage, respectively.