Add isSlashCommandOnly to command interface

src/main/java/me/bobert/netneutrality/context/SlashCommandContext.java

@@ -62,11 +62,11 @@ public class SlashCommandContext extends CommandContext implements InteractionCo
 
     @Override
     public String getSubcommandGroup() {
-        return getFullCommand().split(" ")[2];
+        return event.getSubcommandGroup();
     }
 
     @Override
     public String getSubcommand() {
-        return getFullCommand().split(" ")[1];
+        return event.getSubcommandName();
     }
 }