Add loadAfter plugin setting

src/main/java/emu/grasscutter/plugin/PluginConfig.java

@@ -7,11 +7,13 @@ public final class PluginConfig {
     public String name, description, version;
     public String mainClass;
     public String[] authors;
+    public String[] loadAfter;
 
     /**
      * Attempts to validate this config instance.
      * @return True if the config is valid, false otherwise.
      */
+    @SuppressWarnings("BooleanMethodIsAlwaysInverted")
     public boolean validate() {
         return name != null && description != null && mainClass != null;
     }