Add icons to device tabs

Original report (archived issue) by Shaun Johnstone (Bitbucket: shjohnst, GitHub: shjohnst).

Now that we're adding icons to BLACS, there are a few places within specific devices' tabs where icons could help to make the interface look nicer.

In the pulseblaster tab, the status area could use "tick-circle" and "cross-circle" icons rather than "True" and "False". In this case, I'd also suggest changing the layout to have the status labels spread out horizontally, with the icons below, then the manual control buttons spread horizontally below that, with appropriate play, stop and reset icons added to them.
The camera tab "Check connectivity" button needs an icon to help distinguish it as a button with the new borderless style. I'm not sure which icon would look best, there are a few we could choose from. The server status line can also be replaced by an icon, perhaps either the tick and cross like in the pulseblaster, or "network-status" and "network-status-busy"

These used to be icons when we used GTK, but were not re implemented during the initial port to qt.

labscript-suite / labscript-devices