Text layers from Nav SDK should pick up font stack from map style road label layer

[avi-c]

As we add more UI elements via symbol style layers to the Nav SDK Map style, we should default to using the font stack specified in the road label layer as what is used for any text.

Current examples of Map UI include:

• Route Duration Annotations: Port Route Duration Annotations feature to Maps SDK v10 map styling API #2873
• Intersection Annotations via Electronic Horizon: Annotate intersecting roads and maneuver points along the current route #2928