Add camera mirroring

Add --video-source=camera, and related options:
 - --camera-id=<id>: select the camera by its id (see --list-cameras);
 - --camera-size=<width>x<height>: select the capture size.

Fixed #241 <https://github.com/Genymobile/scrcpy/issues/241>
PR #4213 <https://github.com/Genymobile/scrcpy/pull/4213>

Co-authored-by: Romain Vimont <rom@rom1v.com>
Signed-off-by: Romain Vimont <rom@rom1v.com>

app/data/zsh-completion/_scrcpy

@@ -17,6 +17,8 @@ arguments=(
     '--audio-source=[Select the audio source]:source:(output mic)'
     '--audio-output-buffer=[Configure the size of the SDL audio output buffer (in milliseconds)]'
     {-b,--video-bit-rate=}'[Encode the video at the given bit-rate]'
+    '--camera-id=[Specify the camera id to mirror]'
+    '--camera-size=[Specify an explicit camera capture size]'
     '--crop=[\[width\:height\:x\:y\] Crop the device screen on the server]'
     {-d,--select-usb}'[Use USB device]'
     '--disable-screensaver[Disable screensaver while scrcpy is running]'
@@ -78,6 +80,7 @@ arguments=(
     '--video-codec=[Select the video codec]:codec:(h264 h265 av1)'
     '--video-codec-options=[Set a list of comma-separated key\:type=value options for the device video encoder]'
     '--video-encoder=[Use a specific MediaCodec video encoder]'
+    '--video-source=[Select the video source]:source:(display camera)'
     {-w,--stay-awake}'[Keep the device on while scrcpy is running, when the device is plugged in]'
     '--window-borderless[Disable window decorations \(display borderless window\)]'
     '--window-title=[Set a custom window title]'