chore: Add a workflow to build with feature flag

.github/workflows/build-aztec-feature-flag.yml

@@ -0,0 +1,45 @@
+name: Build with aztec feature flag
+
+on:
+  pull_request:
+  merge_group:
+  push:
+    branches:
+      - master
+
+# This will cancel previous runs when a branch or PR is updated
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.ref || github.run_id }}
+  cancel-in-progress: true
+
+jobs:
+  build-aztec-feature-flag:
+    name: Test on ${{ matrix.os }}
+    runs-on: ${{ matrix.runner }}
+    timeout-minutes: 30
+
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - os: ubuntu
+            runner: ubuntu-latest
+            target: x86_64-unknown-linux-gnu
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup toolchain
+        uses: dtolnay/rust-toolchain@1.71.1
+        with:
+          targets: ${{ matrix.target }}
+
+      - uses: Swatinem/rust-cache@v2
+        with:
+          key: ${{ matrix.target }}
+          cache-on-failure: true
+          save-if: ${{ github.event_name != 'merge_group' }}
+
+      - name: Build with feature flag
+        run: cargo build --features="noirc_frontend/aztec"