QQuickMenu: add enum MenuType that reflects QPlatformMenu::MenuType

On mobile platforms several different popup menu types exist.
E.g on iOS, you have a special popup just for selecting text.
A recent patch added to QtBase added a new enum to QPlatformMenu
that lets UI controls select/hint which one to use. This patch
adds the same enum to QQuickMenu so that we can control this
from Controls as well.

Change-Id: Ibf4bdc84577b5a6527021b1cb15578b56bb4a92e
Add new private control 'EditMenu'

This control will be used as a part of the different
text edit controls for controlling how the edit menu
should work.

Change-Id: Id3ed5795111c37269fce62a97cf4d9bde1b5f6b3
Add EditMenu to input controls

Add EditMenu to TextArea, TextField, ComboBox and
SpinBox.

Change-Id: Ic2fed55c467dde65334006d252f4052430f3f40c
update example

Change-Id: Id7abcc298e7b5586f0b328f431feae3ee7015698