feat(tvix): add //tvix:shell-integration

This provides a shell containing the necessary packages to run the
integration tests too.

//tvix:shell stays the same.

Change-Id: Iac7977cbb7dc085da698993be9baca662d09ff5f
Reviewed-on: https://cl.tvl.fyi/c/depot/+/13164
Tested-by: BuildkiteCI
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: Connor Brewster <cbrewster@hey.com>

tvix/default.nix

@@ -59,6 +59,9 @@ in
   # workspace too.
   shell = (import ./shell.nix { inherit pkgs; });
 
+  # Shell, but with tools necessary to run the integration tests
+  shell-integration = (import ./shell.nix { inherit pkgs; withIntegration = true; });
+
   # Build the Rust documentation for publishing on docs.tvix.dev.
   rust-docs = pkgs.stdenv.mkDerivation {
     inherit cargoDeps src;
@@ -120,6 +123,7 @@ in
   meta.ci.targets = [
     "clippy"
     "shell"
+    "shell-integration"
     "rust-docs"
     "crate2nix-check"
   ];