dbus: add org.apertis.NavigationGuidance1.TurnByTurn API

D-Bus API to send turn-by-turn navigation notifications.

Signed-off-by: Guillaume Desmottes <guillaume.desmottes@collabora.co.uk>
Reviewed-by: Philip Withnall <philip.withnall@collabora.co.uk>
Differential Revision: https://phabricator.apertis.org/D4612