Add CI (grpc#1)

Author: glbrntt

.github/workflows/ci.yaml

@@ -0,0 +1,39 @@
+name: CI
+on:
+  pull_request:
+    branches: [main]
+jobs:
+  preflight:
+    name: License Header and Formatting Checks
+    runs-on: ubuntu-latest
+    container:
+      image: swift:6.0-jammy
+    steps:
+    - name: "Checkout repository"
+      uses: actions/checkout@v4
+    - name: Mark the workspace as safe
+      run: git config --global --add safe.directory ${GITHUB_WORKSPACE}
+    - name: "Install protoc"
+      run: apt update && apt install -y protobuf-compiler
+    - name: "Formatting, License Headers, and Generated Code check"
+      run: |
+        ./dev/sanity.sh
+  unit-tests:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - image: swiftlang/swift:nightly-jammy
+          - image: swift:6.0-jammy
+    name: Build and Test on ${{ matrix.image }}
+    runs-on: ubuntu-latest
+    container:
+      image: ${{ matrix.image }}
+    steps:
+    - uses: actions/checkout@v4
+    - name: 🔧 Build
+      run: swift build ${{ matrix.swift-build-flags }}
+      timeout-minutes: 20
+    - name: 🧪 Test
+      run: swift test ${{ matrix.swift-test-flags }}
+      timeout-minutes: 20