Brigadier Command Support (#8235)

Adds the ability for plugins to register their own brigadier commands 

---------

Co-authored-by: Jake Potrebic <jake.m.potrebic@gmail.com>
Co-authored-by: Jason Penilla <11360596+jpenilla@users.noreply.github.com>
Co-authored-by: Bjarne Koll <git@lynxplay.dev>

test-plugin/src/main/java/io/papermc/testplugin/TestPlugin.java

@@ -8,5 +8,8 @@ public final class TestPlugin extends JavaPlugin implements Listener {
     @Override
     public void onEnable() {
         this.getServer().getPluginManager().registerEvents(this, this);
+
+        // io.papermc.testplugin.brigtests.Registration.registerViaOnEnable(this);
     }
+
 }