Add support for default parameters on Twitch command methods

Methods can have parameters with default values. Currently, if a method including parameters with default values is set to be a Twitch command, it does not behave as intended.

Consider this example:

<img width="422" height="53" alt="Image" src="https://github.com/user-attachments/assets/51345363-b488-4010-9526-91532e32b56e" />

---

```!play```

would default to:

```!play 1```