feat(ops/auto-deploy): Support auto-deploy

Automatically rebuild the current system's NixOS config from the latest checkout
of depot.

Change-Id: I23aa7af50e16e985ac34df214e0905e770316e5e
Reviewed-on: https://cl.tvl.fyi/c/depot/+/4390
Reviewed-by: wpcarro <wpcarro@gmail.com>
Reviewed-by: zseri <zseri.devel@ytrizja.de>
Reviewed-by: grfn <grfn@gws.fyi>
Autosubmit: wpcarro <wpcarro@gmail.com>
Tested-by: BuildkiteCI

ops/modules/default-imports.nix

@@ -8,6 +8,7 @@
 {
   imports = [
     ./automatic-gc.nix
+    ./auto-deploy.nix
     ./tvl-cache.nix
   ];
 }