Encode video using MediaCodec API

Replace screenrecord execution by manual screen encoding using the
MediaCodec API.

The "screenrecord" solution had several drawbacks:
 - screenrecord output is buffered, so tiny frames may not be accessible
   immediately;
 - it did not output a frame until the surface changed, leading to a
   black screen on start;
 - it is limited to 3 minutes recording, so it needed to be restarted;
 - screenrecord added black borders in the video when the requested
   dimensions did not preserve aspect-ratio exactly (sometimes
   unavoidable since video dimensions must be multiple of 8);
 - rotation handling was hacky (killing the process and starting a new
   one).

Handling the encoding manually allows to solve all these problems.

server/src/main/java/com/genymobile/scrcpy/DesktopConnection.java

@@ -65,8 +65,8 @@ public class DesktopConnection implements Closeable {
         outputStream.write(buffer, 0, buffer.length);
     }
 
-    public void sendVideoStream(byte[] videoStreamBuffer, int len) throws IOException {
-        outputStream.write(videoStreamBuffer, 0, len);
+    public OutputStream getOutputStream() {
+        return outputStream;
     }
 
     public ControlEvent receiveControlEvent() throws IOException {