Make inserting gifs more recognizable

[SelinaBuff]

A lot of our user doesn't know that they can insert GIFs. We should add an indicator (e.g. icon) – so it's more visible for everyone.

[Resaki1]

We already have an icon for that, but it only shows up once users have inserted an image URL. Maybe we could show it all the time (or when hovering the note input or something like that)