Add `.TCX` download with turn by turn navigation

Nice work on the new openrouteservice web frontend looks very nice, and renders very nice on mobile compared the classic one 😃

One thing that was added last year in the classic client, thanks to the work of @TheGreatRefrigerator and @marq24 ([#323](https://github.com/GIScience/openrouteservice-app/pull/323)), was the possibility to download in `.tcx` format which is used for turn by turn navigation in handheld GPS unit (bike computers for example).

Here is an exemple of a `.tcx` file generated with the classic ORS frontend

[ors-export-linestring.tcx](https://github.com/GIScience/ors-map-client/files/6398522/ors-export-linestring.tcx.txt)

Could it be possible to port it as well in the new web frontend ?

I see that for `.gpx` you use the [togpx](https://github.com/tyrasd/togpx) package of @tyrasd , maybe can be adapted to `.tcx` ?