Missions - Add a section in icons to change the missions GUI when the user can't yet complete it

[banicola]

Currently you can only change not-completed, can-complete and completed but there's no "no-required-missions" that allows to display something different if the user didn't complete the missions in the required-missions section.

That means that for the user, he sees the GUI with a message saying that he can progress into the mission but his progression doesn't show up since he can't yet do the mission.