Enable redis within the authentik pod, add redis to corp

We put it in the pod because I don't know how to make it accessible to
things in the bod without binding all host addresses. There's probably a
sophisticated way to do it correctly, but I don't want to figure it out
yet.

host/corp/configuration.nix

@@ -19,6 +19,7 @@
 		wget
 	];
 	myModules = {
+		authentik.enable = true;
 		onlyoffice.enable = true;
 		seafile.enable = true;
 		synapse.enable = true;