app_server: do not flush back buffer outside of clipping

Introduce DrawTransaction that automatically hide/show floating overlays
and flush back buffer.

Fixes #15574.

Change-Id: I30088b74fc66cfcd5b2b433b34141e7d496f68a1
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3496
Reviewed-by: Axel Dörfler <axeld@pinc-software.de>

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>

RemoteHWInterface: Use screen change listener to update mode.

This allows dynamic reconfiguration of the size of the virtual desktop
to the dimensions desired by the client.

RemoteDesktop: Switch connection direction and simplify client.

Instead of the server connecting back to a listening client, make it
into a more traditional setup with the server listening on a port and
the client connecting to it.

The client can now either connect directly, unencrypted and without the
ability to trigger listening and specifying a command, or through SSH,
as before with the possibilty to run a target application and causing
the creation of the listener.

With the direction change, there's only the need for one, local, port
forward with SSH, which simplifies things.

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.

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?