Create internal routes to back Conversations

[spolu]

We likely want to discuss a bit what will be the route format but now that the dispatch is merged we can start implementing them

The conversation creation is blocked on my PR: #1324 which is blocked on @PopDaph's PR: #1303 but as soon as the queue gets processed we should be able to fully implement most of the initial routes we'll need

[spolu]

URL I think we'll need:

• POST /api/w/[wId]/assistant/conversations (create new conversation)
• POST /api/w/[wid]/assistant/conversations/[cId]/messages (post new User message)
• GET /api/w/[wId]/assistant/converstaions/[cId] (retrieve converstaion by cId)
• GET /api/w/[wId]/assistant/conversations/[cId]/events (stream conversation events)
• GET /api/w/[wId]/assistant/conversations/[cId]/messages/[mId]/events (stream message events only if message is not an agent message and not succeeded)

Let's standardized all input validation to io-ts (example available in code-base + @fontanierh can help)

[spolu]

yay \o/