If a screen layout cannot be applied, instead of failing to start
WindowServer try to fall back to an auto-generated screen layout with
the devices that are detected.
Also, be a bit smarter about changing the current screen layout.
Instead of closing all framebuffers and bringing them back up, keep
what we can and only change resolution on those that we need to change
them on. To make this work we also need to move away from using an
array of structures to hold compositor related per-screen data to
attaching it to the Screen itself, which makes re-using a screen much
simpler.
It might be the case that we are passing non-movable/non-copyable things
through IPC. In this case, Clang will emit a warning as it can't
generate the requested default move/copy ctor for the IPC message.
To fix this, we use a `#pragma` to make the compiler silently ignore our
request.
The same was the case with the three-way comparison in `Screen`. Since
we don't use the three-way comparison operator anywhere else in our
codebase, we simply use the `==` operator instead.
This sets the stage so that DisplaySettings can configure the screen
layout and set various screen resolutions in one go. It also allows
for an easy "atomic" revert of the previous settings.
