[recorder/feature request] Add the activity type

[truenicoco]

It is very nice that the bike speedometer and run/run+ apps can trigger the recorder app, but it would be even nicer if the exported GPX contained the activity type. It's for instance <type>cycling</type> in the <trk> element.

This field is standard but unfortunately, the values it can take are arbitrary. We could use the values that FitoTrack use, this looks reasonable.

I guess this would require:

• an API change for recorder so that apps that use it can specify the activity type
• a change in the apps to use that new API parameter
• a change in recorder internal storage format
• a change in the recorder GPX exporter

[thyttan]

• And adding corresponding handling for Activity Tracks in Gadgetbridge as well.
  • currently it chooses either walking or running based on speed. If I'm not mistaken.

[bobrippling]

We could alter the format, or keep the format the same and change the filename, to give more ideas for an approach