Implement device-to-computer clipboard copy

On Ctrl+C:
 - the client sends a GET_CLIPBOARD command to the device;
 - the device retrieve its current clipboard text and sends it in a
   GET_CLIPBOARD device event;
 - the client sets this text as the system clipboard text, so that it
   can be pasted in another application.

Fixes <https://github.com/Genymobile/scrcpy/issues/145>

server/src/test/java/com/genymobile/scrcpy/ControlEventReaderTest.java

@@ -174,6 +174,22 @@ public class ControlEventReaderTest {
         Assert.assertEquals(ControlEvent.TYPE_COLLAPSE_NOTIFICATION_PANEL, event.getType());
     }
 
+    @Test
+    public void testParseGetClipboardEvent() throws IOException {
+        ControlEventReader reader = new ControlEventReader();
+
+        ByteArrayOutputStream bos = new ByteArrayOutputStream();
+        DataOutputStream dos = new DataOutputStream(bos);
+        dos.writeByte(ControlEvent.TYPE_GET_CLIPBOARD);
+
+        byte[] packet = bos.toByteArray();
+
+        reader.readFrom(new ByteArrayInputStream(packet));
+        ControlEvent event = reader.next();
+
+        Assert.assertEquals(ControlEvent.TYPE_GET_CLIPBOARD, event.getType());
+    }
+
     @Test
     public void testMultiEvents() throws IOException {
         ControlEventReader reader = new ControlEventReader();