Adds and configures redirect module

[markconroy]

Closes #445

• Adds redirect to composer.json (it will soon be missing since it's removed from localgov_core
• Enables redirect module
• Allows controllers and editors to use redirect

[stephen-cox]

We'll need this released once there's a new release of core removing Redirect (localgovdrupal/localgov_core#227).

Works fine. The editing experience for sites editors and admins is a bit strange – they can only add redirects on a node edit page and a new tab opens for them to do this – but I think we can merge this and review that on another issue.