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/bash-completion/scrcpy

@@ -44,6 +44,8 @@ _scrcpy() {
         --no-video-playback
         --otg
         -p --port=
+        --pause-on-exit
+        --pause-on-exit=
         --power-off-on-close
         --prefer-text
         --print-fps
@@ -97,6 +99,10 @@ _scrcpy() {
             COMPREPLY=($(compgen -W 'unlocked initial 0 1 2 3' -- "$cur"))
             return
             ;;
+        --pause-on-exit)
+            COMPREPLY=($(compgen -W 'true false if-error' -- "$cur"))
+            return
+            ;;
         -r|--record)
             COMPREPLY=($(compgen -f -- "$cur"))
             return