export more then one file format by default

[nutpantz]

While i use kml a lot online, i use gpx a lot offline with applications and for storage.

It would be nice if when i exported my tracks there was a option to always export a second format for those who would use it a lot.

Right now i have to export, change default export format and export again.

[dennisguse]

Doable via https://developer.android.com/reference/androidx/preference/MultiSelectListPreference

Should be relatively easy to do.