Images in block should have alt tags for accessibility

The proposed patch won't unfortunately work if the /user/ path is overridden, for example when using the Rename Admin Paths module.

Ideally we would have a name attribute/key available in the social_networks variable, then we could access it with social_network.name in Twig. Trying to retrieve the auth provider name through the path isn't an ideal solution, as the Twig part becomes harder to understand and the logic becomes a bit hacky.

Also I think the "Social Login" string proposed in the patch could be replaced with something like:

'Authenticate through @social_network_name'|t({'@social_network_name': social_network.name})

That would also be translatable.

Thanks for the feedback, @gaards. I'll be pushing a commit using that format. We can get the social network from the @Network declarations easily enough. As a future enhancement, it might be easier to move the route and img_path declarations there as well instead of using SocialAuthController::setLoginButtonSettings on implementer login. But that would require updates from all implementers so something for a a breaking version perhaps.