Remove modules/legacy

With #32 + #33 built, it should be possible to remove all the logic in https://github.com/alveusgg/chatbot/blob/main/src/modules/legacy.js that handles all the Twitch chat commands for controlling cameras, OBS, etc.

Migrate all the commands as supported from the legacy module into the new commands system with appropriate permissions defined for them (such as a command for full PTZ control, a permission for just preset access, etc.).