nixos/treewide: Move rename.nix imports to their respective modules

A centralized list for these renames is not good because:
- It breaks disabledModules for modules that have a rename defined
- Adding/removing renames for a module means having to find them in the
central file
- Merge conflicts due to multiple people editing the central file

nixos/modules/services/networking/ssh/sshd.nix

@@ -74,6 +74,10 @@ let
 in
 
 {
+  imports = [
+    (mkAliasOptionModule [ "services" "sshd" "enable" ] [ "services" "openssh" "enable" ])
+    (mkAliasOptionModule [ "services" "openssh" "knownHosts" ] [ "programs" "ssh" "knownHosts" ])
+  ];
 
   ###### interface