Application: Remove unneeded exported component

Signed-off-by: Samuel Holland <samuel@sholland.org>

app/src/main/java/com/wireguard/android/Application.java

@@ -55,8 +55,6 @@ public class Application extends android.app.Application {
     public interface ApplicationComponent {
         AsyncWorker getAsyncWorker();
 
-        SharedPreferences getPreferences();
-
         ToolsInstaller getToolsInstaller();
 
         TunnelManager getTunnelManager();