Move locationlabs code into location

The labs feature will still be controlled by location-labs-plugin
config option. They will simply come from the QtLocation module, and
be exposed to QML via the additional qml plugin in
imports/locationlabs.

Change-Id: I133d625708e78ba5d8121a95e45142aae5ec274b
Reviewed-by: Alex Blasche <alexander.blasche@qt.io>