[Maps] Replaces gMaps with MapBox

In order to circumvent the usage quota of Google Maps
the map provider was changed to be MapBox now. Additionally
the maps implementation was refactored to be better extendable
in future.

app/build.gradle

@@ -64,6 +64,9 @@ dependencies {
     implementation 'com.google.android.gms:play-services-maps:19.1.0'
     implementation 'com.google.android.gms:play-services-location:21.3.0'
 
+    //MapBox SDK
+    implementation 'com.mapbox.maps:android:11.11.0'
+
     // Glide
     implementation 'com.github.bumptech.glide:glide:4.16.0'
     implementation 'androidx.preference:preference:1.2.1'