Migrate to kbinani/screenshot for screen adapter

https://github.com/kbinani/screenshot is a library to capture desktop
screen. It is cgo free for Windows, Linux, FreeBSD, OpenBSD, NetBSD, and
Solaris.

pkg/driver/screen/screen.go

@@ -1 +1,79 @@
 package screen
+
+import (
+	"fmt"
+	"image"
+	"io"
+
+	"github.com/kbinani/screenshot"
+	"github.com/pion/mediadevices/pkg/driver"
+	"github.com/pion/mediadevices/pkg/frame"
+	"github.com/pion/mediadevices/pkg/io/video"
+	"github.com/pion/mediadevices/pkg/prop"
+)
+
+type screen struct {
+	displayIndex int
+	doneCh       chan struct{}
+}
+
+func init() {
+	activeDisplays := screenshot.NumActiveDisplays()
+	for i := 0; i < activeDisplays; i++ {
+		priority := driver.PriorityNormal
+		if i == 0 {
+			priority = driver.PriorityHigh
+		}
+
+		s := newScreen(i)
+		driver.GetManager().Register(s, driver.Info{
+			Label:      fmt.Sprint(i),
+			DeviceType: driver.Screen,
+			Priority:   priority,
+		})
+	}
+}
+
+func newScreen(displayIndex int) *screen {
+	s := screen{
+		displayIndex: displayIndex,
+	}
+	return &s
+}
+
+func (s *screen) Open() error {
+	s.doneCh = make(chan struct{})
+	return nil
+}
+
+func (s *screen) Close() error {
+	close(s.doneCh)
+	return nil
+}
+
+func (s *screen) VideoRecord(selectedProp prop.Media) (video.Reader, error) {
+	r := video.ReaderFunc(func() (img image.Image, release func(), err error) {
+		select {
+		case <-s.doneCh:
+			return nil, nil, io.EOF
+		default:
+		}
+
+		img, err = screenshot.CaptureDisplay(s.displayIndex)
+		release = func() {}
+		return
+	})
+	return r, nil
+}
+
+func (s *screen) Properties() []prop.Media {
+	resolution := screenshot.GetDisplayBounds(s.displayIndex)
+	supportedProp := prop.Media{
+		Video: prop.Video{
+			Width:       resolution.Dx(),
+			Height:      resolution.Dy(),
+			FrameFormat: frame.FormatRGBA,
+		},
+	}
+	return []prop.Media{supportedProp}
+}