When multiple images are dragged and dropped onto the image widget,
QuickShow will use LibDesktop::Launcher to launch a new instance
of QuickShow for each item, rather than spawn a child QuickShow
process for each item with posix_spawn.
This allows `proc` and `exec` pledges to be removed :^)
Now that WindowServer broadcasts the system theme using an anonymous
file, we need clients to pledge "recvfd" so they can receive it.
Some programs keep the "shared_buffer" pledge since it's still used for
a handful of things.
