Add Logout Link to Home Page for Select Authentication Providers

For some KnoxSSO providers/IDPs we can accomplish logout by just removing the KnoxSSO cookie. Now that we have a Home Page for Knox, we have somewhere to hang the logout link.

This patch will add such a link as well as add KNOXSSOUT service to the relevant topology. Topology may be knoxsso or the homepage topology depending on CORS and the like.

We do have the unauthenticated URLs feature in SSOCookieProvider in case we need it to get past the authentication provider of the hosting topology.