Route planner: Share not-saved route planned

This is an idea to add "Share as GPX" item to the Route Planner menu (Hamburger in a top-right corner).

Aim - to simplify/speedup the process of planned route uploading to an external navigating device fed by sharing functionality.

E.g. I use Locus as a main route planning tool even when I need to get some route ad hoc (in the middle of somewhere). My routing device is Garmin Edge mounted on a bar. So as of now I have the following chain: 1. Plan a route in Locus -> 2. Save it (in some folder) -> 3. Find new route on main screen -> 4. Hit "Track details" -> 5. Hit "Share" -> 6. Chose "Share as GPX" -> 7. Chose Android app (server) for uploading (e.g. "GPX/FIT Exporter") -> 8. Retrieving the route from Garmin Connect IQ app (client).

So the idea from that perspective is:

- getting rid of steps 2-5;

- not having tmp routes saved in Locus;

- making the use of Locus as a routing tool more straight-forward in "ad hoc" cases with external navigating device.