app_server: recursive scan in /dev/graphics/

* /dev/graphics/virtio_gpu/0 is a valid entry
* app_server doesn't set the initial mode if it's identical; use
0x0 as initial resolution.

Change-Id: Ica0323e6c5d78b39f05499edc93fa9c949b97dc8
Reviewed-on: https://review.haiku-os.org/c/haiku/+/7037
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Jérôme Duval <jerome.duval@gmail.com>

app_server: Make engine accelerant hooks optional.

We don't need them here, or anywhere else for that matter, to run.

app_server memory management: use ObjectDeleter to mark ownership

Make object ownership explicit by use of ObjectDeleter where possible.

Change-Id: I499a00aa3390d1510ae284419e73faffa5166430
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2695
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>
Reviewed-by: Alex von Gluck IV <kallisti5@unixzen.com>

Support for configuring screen backlight

Accelerant interface:
Introduce new hooks B_SET_BRIGHTNESS and B_GET_BRIGHTNESS. Brightness is
a float in the 0..1 range.

App_server:
Forward brightness things between BScreen and the accelerant.

intel_extreme:
Implement the hooks. Note that this only works for laptop panels, but
the driver will pretend to support it in other cases as well.

Screen preferences:
If the accelerant supports the B_GET_BRIGHTNESS hook, allow to set
brightness with a slider. Otherwise, the slidere is hidden and these
changes aren't visible.

app_server: Update overlay hooks after mode change.

* They are supposed to be depending on the current mode.
* This should help with #12613.

AppServer: Organize "HWInterface" classes

* Organize interface classes into directories
* Long term this will assist in the multi-head
interface / accelerant changes.
* local draws to the local hw accelerant
* remote draws to a remote connection (???)
* html5 draws to... an html5 canvas?

AppServer: Organize "HWInterface" classes

* Organize interface classes into directories
* Long term this will assist in the multi-head
interface / accelerant changes.
* local draws to the local hw accelerant
* remote draws to a remote connection (???)
* html5 draws to... an html5 canvas?