Split out redirect filters into separate methods

[earnjam]

The login_redirect filter and the newfold_sso_success_url filters accept differing numbers of parameters. They also require different ways of determining the current user. The former does not have $current_user set and the latter does not have a $user global variable.

To make them both work correctly, and avoid a lot of logic to check values and types of multiple variables, I've created separate methods for each hook that each establish the logged in user, and then pass the url and user on to a single filter_redirect method for evaluation.

[arunshenoy99]

Code looks fine, tested, and it works for the WordPress Login.

[circlecube]

I like using unique callbacks for these scenarios. 👍