add dcc support

[JiPaix]

• Added "dcc" handling to ./plugins/ctcp.ts
  • dcc is excluded from *_reply events since DCCs don't have a reply mechanism
• ./plugins/dcc.ts wraps around these changes
  • client.dcc command
    • Since there's no way to confirm the message was sent (no replies) and the function never throws, it returns the raw string that ctcp() would send
      • I checked other parts of the codebase and throwing doesn't seem to be part of the flow
  • types
    • Any changes or additions just go in the DCC_SCHEMA constant, and everything else cascades automatically (types are generated from it)
      • Additionally, if you want DCC_SCHEMA to handle more complex types, you can extend FieldKindToType

[jeromeludmann]

Thank you very much for this addition, as soon as I have a moment, I will merge the branch.