Gfx::Color is always 4 bytes (it's just a wrapper over u32) it's less
work just to pass the color directly.
This also updates IPCCompiler to prevent from generating
Gfx::Color const &, which makes replacement easier.
We have a new, improved string type coming up in AK (OOM aware, no null
state), and while it's going to use UTF-8, the name UTF8String is a
mouthful - so let's free up the String name by renaming the existing
class.
Making the old one have an annoying name will hopefully also help with
quick adoption :^)
Solitaire and Spider have almost identical code for dragging cards from
one stack to another, so it makes sense to move that here. But using
the term "moving" for them, instead of "focused" which (to me at least)
was not clear what it meant.
As part of this, made a const overload for `Card::rect()`. We need the
non-const one too as it's used for modifying the position of a card
that's being dragged. I plan on changing that soon but we'll see.
For now, the only feature of this is that it sets the background colour
from the `Games::Cards::BackgroundColor` config value. Later, other
card game configuration and shared behaviour can go here, to save
duplicating it in each game.
