Adds three options:
1) Show all (previous behaviour, now default)
2) Show only selection buttons (hide fullscreen and rotate buttons in Browse View)
3) Hide all buttons
This option affects Browse View, Image View Thumbnail Bar, and the Importer tool `gwenview_importer`.
## Three modes in Browse view:
{F5714761, autoplay, loop}
{F5714762, autoplay, loop}
{F5714763, autoplay, loop}
FEATURE: 164847