Add --pause-on-exit

Add an option to make scrcpy pause on exit.

Three behaviors are possible:
 - always pause on exit:
    --pause-on-exit
    --pause-on-exit=true
 - never pause on exit:
    (no option)
    --pause-on-exit=false
 - pause when scrcpy returns with an error (a non-zero exit code):
    --pause-on-exit=if-error

This is useful to prevent the terminal window from automatically
closing, so that error messages can be read.

Refs #3817 <https://github.com/Genymobile/scrcpy/pull/3817>
Refs #3822 <https://github.com/Genymobile/scrcpy/pull/3822>
PR #4130 <https://github.com/Genymobile/scrcpy/pull/4130>

app/data/zsh-completion/_scrcpy

@@ -50,6 +50,7 @@ arguments=(
     '--no-video-playback[Disable video playback]'
     '--otg[Run in OTG mode \(simulating physical keyboard and mouse\)]'
     {-p,--port=}'[\[port\[\:port\]\] Set the TCP port \(range\) used by the client to listen]'
+    '--pause-on-exit=[Make scrcpy pause before exiting]:mode:(true false if-error)'
     '--power-off-on-close[Turn the device screen off when closing scrcpy]'
     '--prefer-text[Inject alpha characters and space as text events instead of key events]'
     '--print-fps[Start FPS counter, to print frame logs to the console]'