Add support for setMiracastMode

Usage is setMiracastMode(WifiP2pManager.MIRACAST_SOURCE) or
setMiracastMode(WifiP2pManager.MIRACAST_SINK) as an example.
Only available for internal use and can be called as long as
driver is active. P2p connection is not needed for it to be
called

Bug: 8493089
Change-Id: I1f87eaf3311212aae980077de26c05651a8cc811

wifi/java/android/net/wifi/p2p/IWifiP2pManager.aidl

@@ -26,5 +26,6 @@ import android.os.Messenger;
 interface IWifiP2pManager
 {
     Messenger getMessenger();
+    void setMiracastMode(int mode);
 }