Add option to select audio source

Pass --audio-source=mic to capture the microphone instead of the device
audio output.

app/data/bash-completion/scrcpy

@@ -7,6 +7,7 @@ _scrcpy() {
         --audio-codec=
         --audio-codec-options=
         --audio-encoder=
+        --audio-source=
         --audio-output-buffer=
         -b --video-bit-rate=
         --crop=
@@ -86,6 +87,10 @@ _scrcpy() {
             COMPREPLY=($(compgen -W 'opus aac raw' -- "$cur"))
             return
             ;;
+        --audio-source)
+            COMPREPLY=($(compgen -W 'output mic' -- "$cur"))
+            return
+            ;;
         --lock-video-orientation)
             COMPREPLY=($(compgen -W 'unlocked initial 0 1 2 3' -- "$cur"))
             return