Approve LDAP users by default.

With this commit all Mastodon users created through LDAP authentication will have attribute approved set to true by default. This prevents new users from having "Your account is still under review." error allowing them to fully login and use Mastodon.

The changes in here are probably a terrible hack as I don't fully understand Mastodon authentication and user creation workflow. While it takes us to where we need today, is probably a good idea to review it sooner than later.