[FEAT] Custom activity states

[i0bs]

Problem Description

discord/discord-api-docs#6345 is on open track. Bots can now set a custom activity state, including custom statuses. We currently only accept activity statuses for watching, playing and streaming.

Proposed Solution

This requires an implementation detail for our client-facing gateway and bot.

Alternatives Considered

No response

Additional Information

No response

Code of Conduct

• I agree to follow the contribution requirements.

[AstreaTSS]

interactions.py doesn't actually do any filtering based off the type, and even has the state field already, but the state itself wasn't being passed through as a payload (via to_dict()). #1527 solves this (and didn't appear on the GitHub log in the server for some reason).