fix(socialaccount): Allow new sociallogin accounts to establish SITE_ID from request

[jeredfloyd]

Commit be779df broke the ability to create new sociallogin accounts in Mailman3 when using django sites framwork, because the request object is not passed down the call chain. This eventually results in the error:

Exception Type: ImproperlyConfigured at /accounts/google/login/callback/
Exception Value: You're using the Django "sites framework" without having set the SITE_ID setting. Create a site in your database and set the SITE_ID setting or pass a request to Site.objects.get_current() to fix this error.

This patch (optionally) passes the request object to resolve this issue.

[coveralls]

coverage: 95.785%. remained the same
when pulling 0278e80 on jeredfloyd:fix-site-id
into 1a8b67d on pennersr:main.