neptune3-ui: add dependency to qtapplicationmanager-native

Neptune examples require appman-packager from qtapplicationmanager-native.
Examples can be enabled with 'examples' PACKAGECONFIG which is inherited
from qt5.inc.

Task-number: AUTOSUITE-1308
Change-Id: I948dcd32eb28ffc29bceaf44dd1bf7f41c3d8288
Reviewed-by: Dominik Holland <dominik.holland@qt.io>