This improves the error message(s) displayed when an error happens while
using a social login to log in / sign up into a Discourse community.
Unfortunately, we can't be super precise in the reason behind the error
(it can be the user clicked "cancel" during the authorization phase, or
any of the plethora of other possible errors) because the reason isn't
provided (either for security reasons, or because it's just hard to do
so in a reliable & consistent way accross all social logins).
The best I could do was to
- add the name of the "social login" provider in the error message
- tweak the copy a bit for the different cases handle
- fix the CSS/HTML to match the one used by the main application
In order to show the name of the provider, we use either the "provider"
or the "strategy" query parameter, or use the name of the authenticator
(if it's the only one enabled).
Internal ref - t/153662
---
**BEFORE**

**AFTER**

Constants should always be only assigned once. The logical OR assignment
of a constant is a relic of the past before we used zeitwerk for
autoloading and had bugs where a file could be loaded twice resulting in
constant redefinition warnings.
We're going to change the default return value of the `primary_email_verified?` method of `Auth::ManagedAuthenticator` to false, so we need to explicitly define the method on authenticators to return true where it makes sense to do so.
Internal topic: t/82084.
This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
Changes to functionality
- Removed syncing of user metadata including gender, location etc.
These are no longer available to standard Facebook applications.
- Removed the remote 'revoke' functionality. No other providers have
it, and it does not appear to be standard practice in other apps.
- The 'facebook_no_email' event is no longer logged. The system can
cope fine with a missing email address.
Data is migrated to the new user_associated_accounts table.
facebook_user_infos can be dropped once we are confident the data has
been migrated successfully.
FIX: warning about popup dimensions when using facebook login
Rules are:
- On account creation we always import
- If you already have an avatar uploaded, nothing is changed
- If you have no avatar uploaded, we upload from facebook on login
- If you have no avatar uploaded, we select facebook unless gravatar already selected
This also fixes SSO issues where on account creation accounts had missing avatar uploads