Do not suppress infobar if infobar is just closed

Currently any infobar that is closed is supressed until Qt Creator is restarted.

Proposal: Do not supress infobar if it is simply closed.

If for example a .ui.qml file is opened we show an infobar. If this infobar is closed,
then we will show the infobar again if another or the same ui.qml is opened again.

To get rid of infobar the user has to click "Do not show again".