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/scrcpy.1

@@ -43,6 +43,12 @@ The values are expressed in the device natural orientation (typically, portrait
 .B \-\-max\-size
 value is computed on the cropped size.
 
+.TP
+.B \-d, \-\-select\-usb
+Use USB device (if there is exactly one, like adb -d).
+
+Also see \fB\-e\fR (\fB\-\-select\-tcpip\fR).
+
 .TP
 .BI "\-\-disable-screensaver"
 Disable screensaver while scrcpy is running.
@@ -62,6 +68,12 @@ Add a buffering delay (in milliseconds) before displaying. This increases latenc
 
 Default is 0 (no buffering).
 
+.TP
+.B \-e, \-\-select\-tcpip
+Use TCP/IP device (if there is exactly one, like adb -e).
+
+Also see \fB\-d\fR (\fB\-\-select\-usb\fR).
+
 .TP
 .BI "\-\-encoder " name
 Use a specific MediaCodec encoder (must be a H.264 encoder).