Conversations API for Pleroma API

Kenoma will want to use the conversations api for the chat system. I haven't looked too deep into how it works, but documentation is here:

https://docs-develop.pleroma.social/backend/API/pleroma_api/#pleroma-conversations

The documentation seems a bit incomplete, so also checking out mastodon's equivalent is a good idea:

https://docs.joinmastodon.org/api/rest/timelines/#get-api-v1-conversations

https://docs.joinmastodon.org/api/entities/#conversation