Replace (un)checkAction with toggleAction (1/3)

Replace (un)checkAction with toggleAction (1/3)

Add toggleAction to QAccessibleActionInterface.

This change is split into separate modules, thus we have to be careful
of not breaking qtdeclarative, which currently depends (un)checkAction.
Therefore we apply the patches in this order:
1. Add toggleAction to QAccessibleActionInterface (in qtbase)
2. Replace all references to (un)checkAction with toggleAction
   (in qtdeclarative)
3. Remove all references to (un)checkAction (in qtbase)

Change-Id: Ib00fee3139eeabbece97295bc3d713ab119c92e6
Reviewed-by: Morten Johan Sørvig <morten.sorvig@nokia.com>