Add setBearing overload to rotate around a coordinate

This patch adds an overload for setBearing in QDeclarativeGeoMap to
rotate the map around a specific QGeoCoordinate.

[ChangeLog][QtLocation][QDeclarativeGeoMap] Added setBearing overload to
rotate the map around a given QGeoCoordinate.

Change-Id: I5d2428d852b0c3537f4a1cdb1925c059788c45c5
Reviewed-by: Alex Blasche <alexander.blasche@qt.io>