Remane private QQuickAction into QQuickStateAction

Remane private QQuickAction into QQuickStateAction

This avoid symbol conflicts when statically linking with Qt Quick
Controls, that has its own QQuickAction class and which may become
public some day. (QQuickPropertyAction might be a more apt name, but
it's already taken).

Change-Id: Ia9514d63d38295603a89d8ec5a88815a651380f7
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@digia.com>
Reviewed-by: Jens Bache-Wiig <jens.bache-wiig@digia.com>