Fediverse-based authentication (#1846)

* Able to authenticate user against IndieAuth. For #1273

* WIP server indieauth endpoint. For https://github.com/owncast/owncast/issues/1272

* Add migration to remove access tokens from user

* Add authenticated bool to user for display purposes

* Add indieauth modal and auth flair to display names. For #1273

* Validate URLs and display errors

* Renames, cleanups

* Handle relative auth endpoint paths. Add error handling for missing redirects.

* Disallow using display names in use by registered users. Closes #1810

* Verify code verifier via code challenge on callback

* Use relative path to authorization_endpoint

* Post-rebase fixes

* Use a timestamp instead of a bool for authenticated

* Propertly handle and display error in modal

* Use auth'ed timestamp to derive authenticated flag to display in chat

* Fediverse chat auth via OTP

* Increase validity time just in case

* Add fediverse auth into auth modal

* Text, validation, cleanup updates for fedi auth

* Fix typo

* Remove unused images

* Remove unused file

* Add chat display name to auth modal text

auth/persistence.go

@@ -55,6 +55,7 @@ func GetUserByAuth(authToken string, authType Type) *user.User {
 		Type:  string(authType),
 	})
 	if err != nil {
+		log.Errorln(err)
 		return nil
 	}