ci: build cloud-hypervisor from latest upstream release

Ubuntu does not package Cloud Hypervisor, so the integration test cannot
rely on apt for that binary. Resolve the latest upstream release tag,
check out that source, install the needed dev packages, build with
cargo --release, and reuse the existing rust-cache target-dir caching
for later runs.

Author: phip1611

.github/workflows/rust.yml

@@ -58,13 +58,44 @@ jobs:
         with:
           key: "integration-test"
           cache-directories:
+            ./.ci/cloud-hypervisor-target
             ./integration-test/x86/target
             ./integration-test/riscv/target
-      - name: Install QEMU
+      - name: Resolve latest Cloud Hypervisor release
+        id: chv_release
+        run: |
+          tag=$(
+            curl -fsSL \
+              https://api.github.com/repos/cloud-hypervisor/cloud-hypervisor/releases/latest \
+              | python3 -c 'import json,sys; print(json.load(sys.stdin)["tag_name"])'
+          )
+          echo "tag=$tag" >> "$GITHUB_OUTPUT"
+      - name: Install integration-test dependencies
         run: |
           sudo apt-get update
-          sudo apt-get install -y qemu-system-x86 qemu-system-misc
-
+          # QEMU
+          sudo apt-get install -y
+            qemu-system-misc \
+            qemu-system-x86
+          # Building cloud Hypervisor
+          sudo apt-get install -y \
+            libssl-dev \
+            pkg-config
+      - name: Check out latest Cloud Hypervisor release source
+        env:
+          CHV_TAG: ${{ steps.chv_release.outputs.tag }}
+        run: |
+          rm -rf ./.ci/cloud-hypervisor-src
+          git clone --depth 1 --branch "$CHV_TAG" \
+            https://github.com/cloud-hypervisor/cloud-hypervisor.git \
+            ./.ci/cloud-hypervisor-src
+      - name: Build Cloud Hypervisor from latest upstream release
+        env:
+          CARGO_TARGET_DIR: ${{ github.workspace }}/.ci/cloud-hypervisor-target
+        working-directory: ./.ci/cloud-hypervisor-src
+        run: cargo build --release
+      - name: Verify Cloud Hypervisor installation
+        run: ./.ci/cloud-hypervisor-target/release/cloud-hypervisor --version
       - name: Verify QEMU installation
         run: |
           qemu-system-i386 --version
@@ -73,6 +104,8 @@ jobs:
         working-directory: integration-test
         run: make
       - name: Run
+        env:
+          PATH: ${{ github.workspace }}/.ci/cloud-hypervisor-target/release:${PATH}
         working-directory: integration-test
         run: make run