feat(auth): Log login source (#8875)
feat(auth): Log login source (#8875)

We're implementing the ability to log in via Github and VSTS in addition to regular login and want to get a sense of the numbers.
mvaled/sentry,ifduyue/sentry,looker/sentry,looker/sentry,ifduyue/sentry,mvaled/sentry,mvaled/sentry,beeftornado/sentry,mvaled/sentry,mvaled/sentry,looker/sentry,beeftornado/sentry,mvaled/sentry,looker/sentry,beeftornado/sentry,ifduyue/sentry,ifduyue/sentry,ifduyue/sentry,looker/sentry