Rename --no-mirror to --no-playback

This option impacts video and audio _playback_. For example, if we use
V4L2, the device is still "mirrored" (via V4L2), even if playback is
disabled. Therefore, "playback" is more approriate than "mirror".

The initial option --no-display option was renamed to --no-mirror by
commit 6928acdeac, but this has never been
released, so it is ok to rename it one more time.

Refs #3978 <https://github.com/Genymobile/scrcpy/pull/3978#issuecomment-1549420103>
PR #4033 <https://github.com/Genymobile/scrcpy/pull/4033>

app/data/bash-completion/scrcpy

@@ -33,7 +33,7 @@ _scrcpy() {
         --no-clipboard-autosync
         --no-downsize-on-error
         -n --no-control
-        -N --no-mirror
+        -N --no-playback
         --no-key-repeat
         --no-mipmaps
         --no-power-on