ci: Add test workflow for bootc-ubuntu-setup action

Add automated testing for the bootc-ubuntu-setup action to verify
it functions correctly after updates like the bcvk version bump.

The workflow includes two test jobs:
- Basic setup without libvirt (podman, just, /dev/kvm)
- Full setup with libvirt (bcvk, virsh, libvirt configuration)

Assisted-by: Claude Code (Sonnet 4.5)
Signed-off-by: Colin Walters <[email protected]>

Author: cgwalters

.github/workflows/test-bootc-ubuntu-setup.yml

@@ -0,0 +1,30 @@
+name: Test Bootc Ubuntu Setup
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    paths:
+      - 'common/.github/actions/bootc-ubuntu-setup/**'
+      - '.github/workflows/test-bootc-ubuntu-setup.yml'
+
+jobs:
+  test-basic-setup:
+    runs-on: ubuntu-24.04
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Run bootc-ubuntu-setup
+        uses: ./common/.github/actions/bootc-ubuntu-setup
+
+  test-libvirt-setup:
+    runs-on: ubuntu-24.04
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Run bootc-ubuntu-setup with libvirt
+        uses: ./common/.github/actions/bootc-ubuntu-setup
+        with:
+          libvirt: 'true'