iOS: Implement support for native menus

Change-Id: I2c7278697499aa046ac7b1240b7bc713ad1fc709
QPlatformMenu: add OptionMenu and ActionMenu to MenuType

Change-Id: I106efe995287df469f42bec51a0344098b05b8e2
QIOSMenu: use UIActionSheet for actions menu

Change-Id: Ibc4dc3529a387ceffdd0178a661fc76c1a9f089f