Make it possible for extensions to influence the redirects on the management endpoint

WFLY-14735 is adding an extension that will add an /authentication or /login context to the management interface, we will need users to be redirected to this before they go to the console endpoint.

The simplest may be to have a sequence:
/
/authentication
/console

Then when the authentication context is added it will be able to take over the redirects.

More complex would be stick to the original:
/
/console

But then the extension can define the root redirect:
/
/authentication

Then the new extension will handle redirects after /authentication.