[FEAT] Dual monitor Wayland - Pending external development

[thelamer]

I want this, but after setting up Smithay in pixelflux to support a second monitor creation it all works I can span the two monitors resize them, re-arrange them.

The break is in the DEs running under it, nothing works.

KDE lacks tools because of how we are running it so you get mirrored versions of a single display at best and garbage output at worst.
Labwc and basically everything else just runs as a nested surface and runs it's own wl-roots proto including the unstable output manager used by wlr-randr.

You can manually make a labwc config file but it is at launch only you cannot hot load it and the surfaces stack on the same monitor by default.

Basically with everything I have tested there is no automagic way to plug in and unplug a monitor that an underlying DE will understand in this type of userspace stack.

The monitors and layout of spaces is correct in smithay, I just think none of this has been tested yet which is why I have created this issue to check into this in a couple months and see if there is any changes.

interface: 'wl_output',                                  version:  4, name: 24
	name: HEADLESS-1
	description: Pixelflux - Virtual-1 - HEADLESS-1
	x: 0, y: 0, scale: 1,
	physical_width: 1920 mm, physical_height: 1080 mm,
	make: 'Pixelflux', model: 'Virtual-1',
	subpixel_orientation: unknown, output_transform: normal,
	mode:
		width: 1920 px, height: 1080 px, refresh: 60.000 Hz,
		flags: current preferred
interface: 'wl_output',                                  version:  4, name: 25
	name: HEADLESS-2
	description: Pixelflux - Virtual-2 - HEADLESS-2
	x: 1920, y: 0, scale: 1,
	physical_width: 1920 mm, physical_height: 1080 mm,
	make: 'Pixelflux', model: 'Virtual-2',
	subpixel_orientation: unknown, output_transform: normal,
	mode:
		width: 1920 px, height: 1080 px, refresh: 60.000 Hz,
		flags: current preferred