App: Export GPX (offline) shaping points

It’s already possible to export routes without internet in GPX format (with waypoint names).
(besides using the offline Kurviger format)

Via points + shaping points are currently exported in GPX together without any separation.

We can add a separation, probably using some available GPX point element, e.g. “type”:
Element: type: Type (classification) of the waypoint.

Related to:

Implemented in Kurviger 1.14.13.