app,gpu: move errDeviceLost from package app to package gpu

The Vulkan backend can return device lost error from more than just
Present.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

gpu/internal/driver/driver.go

@@ -54,6 +54,8 @@ type Device interface {
 	Release()
 }
 
+var ErrDeviceLost = errors.New("GPU device lost")
+
 type LoadDesc struct {
 	Action     LoadAction
 	ClearColor f32color.RGBA