Turn framebuffer drivers into capture clients

This patch replaces the use of the "Framebuffer" session interface by
the new "Capture" session interface in all framebuffer drivers. Thanks
to this change, those drivers have become mere clients of the nitpicker
GUI server now, and are no longer critical for the liveliness of the GUI
server.

The patch touches the following areas:

- The actual driver components. The new versions of all drivers have
  been tested on the respective hardware. Generally, the drivers
  have become simpler.

- The drivers_interactive packages for various boards. The drivers
  subsystem no longer provides a "Framebuffer" service but needs a
  valid route to the "Capture" service provided by nitpicker.

- The driver manager of Sculpt OS.

- This patch changes the role of the test-framebuffer component from a
  framebuffer client to a capture server so that drivers (capture clients)
  can be directly connected to the test component without the nitpicker
  server.

- Framebuffer driver no longer support the unbuffered mode.

- The fb_bench.run script is no longer very meaningful because it
  interplays solely with nitpicker, not with the driver directly.

- All run scripts for graphical scenarios and the related depot
  archives got adapted to the change.

Fixes #3813

repos/gems/src/test/driver_manager/main.cc

@@ -16,7 +16,6 @@
 #include <base/attached_rom_dataspace.h>
 #include <base/allocator_avl.h>
 #include <base/heap.h>
-#include <framebuffer_session/connection.h>
 #include <input_session/connection.h>
 #include <block_session/connection.h>
 
@@ -32,6 +31,7 @@ struct Test::Main
 
 	Attached_rom_dataspace _config        { _env, "config" };
 	Attached_rom_dataspace _block_devices { _env, "block_devices" };
+	Attached_rom_dataspace _displays      { _env, "displays" };
 
 	static bool _attribute_matches(char const *attr, Xml_node expected, Xml_node checked)
 	{
@@ -113,6 +113,14 @@ struct Test::Main
 			Block::Connection<> block(_env, &packet_alloc, 128*1024, label.string());
 		});
 
+		if (_config.xml().has_sub_node("check_displays")) {
+			_displays.update();
+			if (!_displays.xml().has_sub_node("display"))
+				return;
+
+			log("available displays: ", _displays.xml());
+		}
+
 		log("all expected devices present and accessible");
 	}
 
@@ -121,12 +129,6 @@ struct Test::Main
 
 	Main(Env &env) : _env(env)
 	{
-		if (_config.xml().has_sub_node("check_framebuffer")) {
-			log("connect to framebuffer driver");
-			Framebuffer::Mode mode { .area = { 640, 480 } };
-			Framebuffer::Connection fb(_env, mode);
-		}
-
 		if (_config.xml().has_sub_node("check_input")) {
 			log("connect to input driver");
 			Input::Connection input(_env);