Add terraform-ls to emacs.

nix/configuration/roles/emacs/default.nix

@@ -131,6 +131,7 @@ in
                     final.cmake # Used by cmake-language-server
                     final.rust-analyzer
                     final.nodePackages_latest.prettier # Format yaml, json, and JS
+                    final.terraform-ls
                   ]
                 }
               '';