Add a workflow that gives copilot access to the nix environment

Author: mrinalwadhwa

.github/workflows/copilot.yml

@@ -0,0 +1,36 @@
+name: Copilot
+
+permissions:
+  contents: read
+
+on:
+  push:
+    paths:
+      - .github/workflows/copilot.yml
+  pull_request:
+    paths:
+      - .github/workflows/copilot.yml
+  workflow_dispatch:
+    inputs:
+      commit_sha:
+        description: Git commit sha, on which, to run this workflow
+
+defaults:
+  run:
+    shell: nix develop ./tools/nix --command bash {0}
+
+jobs:
+  copilot-setup-steps:
+    name: Copilot - setup
+    runs-on: ubuntu-24.04
+    steps:
+      - name: Checkout
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+        with:
+          ref: ${{ github.event.inputs.commit_sha }}
+
+      - name: Setup Nix
+        id: setup-nix
+        uses: ./.github/actions/setup_nix
+        with:
+          cache-id: all