automatically show the file (browse) dialog when selecting to set an icon as a PNG/SVG

[Jeff Almasol]

1. open KBar Settings
2. click Add Button > Apply Effect
3. click ICON, then change the popup to "Pick a custom PNG/SVG file"

--> i still have to click BROWSE.

for the other two options for icons, i can either start typing the label or selecting an icon. just trying to save a click.

[Rafi Khan]

The UI framework I'm using makes this not trivial. Might reconsider this in 2.0.