Allow Matrix verification in the Lemmy software.

An idea I just recently had was to add the ability for users to verify accounts on Lemmy using Matrix accounts as an alternative to Email. I think this would be a great idea since it allows for users to have choices in how they sign-up to their accounts. It would also encourage more usage of Matrix accounts for secure messaging between users, a feature which hasn't seen much use among users here.

It would still in most cases be optional and server admins could choose if it's even enabled at all, just like how email verification is right now. Even if it was required I feel like it should be a supplement to email in most cases but servers could choose to make it required instead of email, especially in cases where they don't have a mail server.

The different states of it could be: - Matrix or Email Required - Matrix required, Email optional - Email Required, Matrix optional - Email and/or Matrix Optional

Servers could also choose to have the matrix account used for verification be on a server that isn't their own, though this would generally be discouraged and would be specifically for admins who don't have their own infrastructure (like the ones who don't have a mail server).

I made an issue on the Main Lemmy github, feel free to check it out here. Feel free to either share your opinions on this here or on the Github issue.