Add `supabase.auth.addSSOConnection` method

Now the only way to create an SSO connection is via the CLI, this is not great because usually you would have a page in your dashboard to let users add their metadata URL and create an SSO connection

To do this supabase client should expose a method like addSSOConnection, similar to the [supabase sso add command](

Not sure if this method should be in the auth namespace, it would make sense to add a new one called sso maybe