gh-actions: CI action for Dex

Create a GH Action that tests if:
1. Dex manifests can be applied in a KinD K8s 1.22 cluster
2. All pods can become ready

Signed-off-by: Kimonas Sotirchos <kimwnasptd@arrikto.com>

.github/workflows/dex_kind_test.yaml

@@ -0,0 +1,30 @@
+name: Build & Apply Dex manifests in KinD
+on:
+  pull_request:
+    paths:
+      - common/dex/base/**
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v3
+
+    - name: Install KinD
+      run: ./tests/gh-actions/install_kind.sh
+
+    - name: Create KinD Cluster
+      run: kind create cluster --config tests/gh-actions/kind-cluster-1-22.yaml
+
+    - name: Install kustomize
+      run: ./tests/gh-actions/install_kustomize.sh
+
+    - name: Install Istio
+      run: ./tests/gh-actions/install_istio.sh
+
+    - name: Build & Apply manifests
+      run: |
+        cd common/dex
+        kustomize build overlays/istio | kubectl apply -f -
+        kubectl wait --for=condition=Ready pods --all --all-namespaces --timeout 180s