Fix nil access for inactive auth sources.
> Render failed, failed to render template:
user/settings/security/security, error: template error:
builtin(static):user/settings/security/accountlinks:32:20 : executing
"user/settings/security/accountlinks" at <$providerData.IconHTML>: nil
pointer evaluating oauth2.Provider.IconHTML
Code tries to access the auth source of an `ExternalLoginUser` but the
list contains only the active auth sources.
e378545f30