Add an option to not display the buttons when the search bar is empty

[baptisteArno]

If checking this option made the buttons disappear, it would already be very useful... but it only adds a search field among the options:

https://i.imgur.com/RHbcsSt.png

Originally posted by @tibehrius in https://github.com/baptisteArno/typebot.io/discussions/336#discussioncomment-6755239