title: xamarin get location at cross-platform
body: <p>i want to get location (use gps) at xamarin.form - that is, in cross platform.
  but i can't find. only platform-dependent (at android, at ios, etc.)</p>
  
  <p>if you know, please share to me !
  (i found xamarin.mobile - geolocation, but it is also platform-dependent T^T)</p>