Adds support for choosing to present the full resolution
independently to each eye when using side-by-side or
top-and-bottom 3D.

Fixes https://bugs.dolphin-emu.org/issues/13593. Before, it would attempt to
use the old shader, which did not exist for the new stereo mode. Changing the
postprocessing shader afterwards would work properly, although passive 3D only
has one option, so it was just broken without restarting Dolphin.

This also fixes the UI not updating when using one of the stereo toggle hotkeys.

The old tooltip description box used GraphicsWidget to provide shared
code to the Graphics config panes for adding descriptions to their
settings.

The description box has been replaced by BalloonTips and serves no
further purpose, so remove it and have the Graphics panes derive from
QWidget instead.

GraphicsSlider is used by the panes in the Graphics config window to
create sliders that change their associated config setting, and update
their own state when something else changes the config setting.

Despite its current name nothing about this class is particular to the
Graphics window, so renaming it to ConfigSlider better reflects its
purpose. This should also make it less confusing when ConfigSliders are
added to other config panes.

GraphicsChoice is used by the panes in the Graphics config window to
create combo boxes that change their associated config setting, and
update their own state when something else changes the config setting.

Despite its current name nothing about this class is particular to the
Graphics window, so renaming it to ConfigChoice better reflects its
purpose. This should also make it less confusing when ConfigChoices are
eventually added to the other config windows.

GraphicsBool is used by the panes in the Graphics config window to
create checkboxes that change their associated config setting, and
update their own state when something else changes the config setting.

Despite its current name nothing about this class is particular to the
Graphics window, so renaming it to ConfigBool better reflects its
purpose. This should also make it less confusing when ConfigBools are
eventually added to the other config windows.