For saving in custom directory

[AlbertArakelyan]

1. Instead of suggesting to pick a save directory directly, put a toggle next to the convert button with label "Save at custom directory".
2. Also add an info "i" tooltip which will tell "This will prevent the audio to be played in the application directly".
3. When it is not toggled save at default "audio directory", when it is toggled open dialog.saveDialog.
4. For this we should pass isCustomDirectory parameter through invoke function.