global: get rid of nonnull gradle hack

Hacking things up via gradle is not right, and package-info.java poses
problems with two modules, so instead we just apply it manually to every
class.

Remember to add this to new classes!

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

tunnel/src/main/java/com/wireguard/config/BadConfigException.java

@@ -5,10 +5,13 @@
 
 package com.wireguard.config;
 
+import com.wireguard.util.NonNullForAll;
+
 import androidx.annotation.Nullable;
 
 import com.wireguard.crypto.KeyFormatException;
 
+@NonNullForAll
 public class BadConfigException extends Exception {
     private final Location location;
     private final Reason reason;