Update return types as optional via named arg

- Update the modified slash commands for chat sending to use the named arg
- Add `slashCommandReturnHelper` for shared funcitonality on return type usage

public/scripts/slash-commands/SlashCommandCommonEnumsProvider.js

@@ -36,6 +36,7 @@ export const enumIcons = {
     message: '💬',
     voice: '🎤',
     server: '🖥️',
+    popup: '🗔',
 
     true: '✔️',
     false: '❌',