Webhooks and Bridging Within Threads and Forum Posts (When Those Get Added)

Problem

In the future, when threads and forums get added, we need a way to bridge contents of threads and forum posts. Discord doesn't have webhooks for threads and forum posts, but Matrix has allowed for contents of threads to be bridged(but in a bridge to Discord, that was messy since there was no way to bridge that to a thread on Discord, so it ended up just posting it out into the channel).

Proposal

Add webhooks to threads, forum posts, and any other type of post structures and channels. When a thread is created in a bridged channel, it should also bridge that thread and its contents. When a post is made in a forum channel, it should bridge that post and its contents.

Notes

This may not translate well to other platforms that don't give threads and forum posts webhook abilities or other bridging capabilities(such as Discord). I have also suggested this for Stoat: https://github.com/orgs/stoatchat/discussions/1499