feat: introduce .idx/dev.nix for Google IDX support

Google IDX is a cloud-based toolset for building, testing, and deploying
apps. To support `patch-hub` development in this platform, add file
`.idx/dev.nix` with the project specific configurations.

[Maintainer edits]
- Rephrase commit message

Signed-off-by: OJarrisonn <[email protected]>
Reviewed-by: David Tadokoro <[email protected]>
Signed-off-by: David Tadokoro <[email protected]>

Author: OJarrisonn

.idx/dev.nix

@@ -0,0 +1,33 @@
+# To learn more about how to use Nix to configure your environment
+# see: https://developers.google.com/idx/guides/customize-idx-env
+{ pkgs, ... }: {
+  channel = "stable-23.11";
+  # Use https://search.nixos.org/packages to find packages
+  packages = with pkgs; [
+    gitFull
+    rustup
+    b4
+    bat
+    delta
+    diff-so-fancy
+    gcc
+  ];
+
+  # Sets environment variables in the workspace
+  env = {};
+  idx = {
+    # Search for the extensions you want on https://open-vsx.org/ and use "publisher.id"
+    extensions = [
+      "franneck94.vscode-rust-extension-pack"
+    ];
+
+    previews.enable = false;
+
+    workspace = {
+      onCreate = {
+        rust = "rustup default stable";
+        first-build = "cargo build";
+      };
+    };
+  };
+}