Template fixes

Template fixes addressing Alex's comments and other things I put to one side on the first pass.

Includes a fix to autocompilation (which was broken due to a name change)

What to do about the contact link? Shall I take it out until we do this page? Link to some existing page?
I know rendering this view is what we currently do in Backdrop, but I don't know why we do that. Can we follow the pattern used by all the other admin apps, which is to [redirect immediately to the Signon `sign_out` path](https://github.com/alphagov/gds-sso/blob/v9.3.0/app/controllers/authentications_controller.rb#L16-19)?