First pass at invite-only migration. (#1949)

First pass at invite-only migration. (#1949)

* First pass at invite-only migration.

* Implement email verification (fixes #219)

* remove unwrap

* Adding views and functionality to registration application. #209

* Add private instance site column, and back end checks.

* Adding some message fields to LoginResponse

* Adding private instance to site setup.

* A few additions:

- Add a DeleteAccount response.
- RegistrationApplicationView now has the safe LocalUserSettings.
- Adding VerifyEmail to websocket API, added a proper response type.

* Adding and reorganizing some email helpers.

* A few fixes for private sites:

- Added a check_registration_application function.
- Only send a verification email if its been changed.
- VerifyEmail now returns LoginResponse.
- Deleting the old tokens after a successful email verify.
- If port is missing on email config, display a better error message.

* Version 0.15.0-rc.3

* Adding published to email_verification table.

* Adding fixes from comments.

* Version 0.15.0-rc.4

* Adding modlog private site check.

* Version 0.15.0-rc.6

Co-authored-by: Felix Ableitner <me@nutomic.com>