Fix Android crash in release build due to ProGuard

ProGuard optimizes out methods it considers unused in release build, but methods only called from native code appear unused.

The ProGuard rule was broken from renaming the main activity and also did not consider the server service yet.

scripts/android/files/proguard-rules.pro

@@ -16,7 +16,7 @@
 # debugging stack traces.
 -keepattributes SourceFile,LineNumberTable
 
--keepclassmembers, allowoptimization public class org.ddnet.client.NativeMain {
+-keepclassmembers, allowoptimization public class org.ddnet.client.* {
 	*;
 }