Add option to select USB or TCP/IP devices

If several devices are connected (as listed by `adb devices`), it was
necessary to provide the explicit serial via -s/--serial.

If only one device is connected via USB (respectively, via TCP/IP), it
might be convenient to select it automatically. For this purpose, two
new options are introduced:
 - -d/--select-usb: select the single device connected over USB
 - -e/--select-tcpip: select the single device connected over TCP/IP

PR #3005 <https://github.com/Genymobile/scrcpy/pull/3005>

app/src/options.c

@@ -60,4 +60,6 @@ const struct scrcpy_options scrcpy_options_default = {
     .downsize_on_error = true,
     .tcpip = false,
     .tcpip_dst = NULL,
+    .select_tcpip = false,
+    .select_usb = false,
 };