ItemDelegate: improve accessible properties

Make pressAction signal connected so a screen reader can trigger the action.

As a list item, it has no press action by default. Ref: https://invent.kde.org/qt/qt/qtdeclarative/-/blob/e1b190c8d644c1f5489f96fa8566f85470078013/src/quick/accessible/qaccessiblequickitem.cpp#L477 and https://invent.kde.org/qt/qt/qtdeclarative/-/blob/e1b190c8d644c1f5489f96fa8566f85470078013/src/quicktemplates/qquickitemdelegate.cpp#L97