LibGPU+LibVirtGPU: Allow loading the driver and instantiating the device

This adds LibVirtGPU to the list of allowed drivers in LibGPU and adds a
factory method to create the device to libVirtGPU.

Userland/Libraries/LibGPU/Driver.cpp

@@ -13,16 +13,19 @@
 namespace GPU {
 
 // FIXME: Think of a better way to configure these paths. Maybe use ConfigServer?
+// clang-format off
 static HashMap<DeprecatedString, DeprecatedString> const s_driver_path_map
 {
 #if defined(AK_OS_SERENITY)
     { "softgpu", "libsoftgpu.so.serenity" },
+    { "virtgpu", "libvirtgpu.so.serenity" },
 #elif defined(AK_OS_MACOS)
     { "softgpu", "liblagom-softgpu.dylib" },
 #else
     { "softgpu", "liblagom-softgpu.so.0" },
 #endif
 };
+// clang-format on
 
 static HashMap<DeprecatedString, WeakPtr<Driver>> s_loaded_drivers;