This is needed to have code for creating an in-memory sRGB profile using
the (floating-ppoint) numbers from the sRGB spec and having the
fixed-point values in the profile match what they are in other software
(such as GIMP).
It has the side effect of making the FixedPoint ctor no longer constexpr
(which seems fine; nothing was currently relying on that).
Some of FixedPoint's member functions don't round yet, which requires
tweaking a test.
As a nearby comment says, "This is a terrible approximation".
This doesn't make things less terrible, but it does make things
more correct in the given framework of terribleness.
Fixes#17156.
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 :^)
Rather than casting the FixedPoint to double, format the FixedPoint
directly. This avoids using floating point instruction, which in
turn enables this to be used even in the kernel.
