Add method to remove sub commands from command handler (#3941)

api/src/main/java/com/viaversion/viaversion/api/command/ViaVersionCommand.java

@@ -34,6 +34,13 @@ public interface ViaVersionCommand {
      */
     void registerSubCommand(ViaSubCommand command);
 
+    /**
+     * Removes a subcommand by name, can be used to unload default subcommands which are not supported
+     * on the platform.
+     * @param name Subcommand name
+     */
+    void removeSubCommand(String name);
+
     /**
      * Check if a subcommand is registered.
      *

common/src/main/java/com/viaversion/viaversion/commands/ViaCommandHandler.java

@@ -57,6 +57,11 @@ public abstract class ViaCommandHandler implements ViaVersionCommand {
         commandMap.put(command.name().toLowerCase(Locale.ROOT), command);
     }
 
+    @Override
+    public void removeSubCommand(final String name) {
+        commandMap.remove(name.toLowerCase(Locale.ROOT));
+    }
+
     @Override
     public boolean hasSubCommand(String name) {
         return commandMap.containsKey(name.toLowerCase(Locale.ROOT));