Fix console not being blocked by IT_CV_STRING

On text fields in menus, only some of them were actually blocking the console from being opened. The ones that weren't were all marked with IT_CV_STRING, and due to a logical error on the handler, the key event that maps to that character was forwarded to the console handler, causing the console to be openable by the console key.

This patch fixes this by returning true in the key handler that case, to make sure the key event won't be passed forward to the console handler.