Build CI images in parallel (#7296)

* Factor out common setup steps

* Re-order

* Split independent builds into parallel jobs

* Cache jetson builds

* Use zstd compression

* Switch from gha cache to registry cache

A CI run (four images cached with mode-max) populates the cache with 295
cache entries totalling 23.44 GB. This exceeds gha's 10GB limit, causing
trashing. Try with a registry instead.

* Enable manual CI runs

.github/actions/setup/action.yml

@@ -0,0 +1,39 @@
+name: 'Setup'
+description: 'Set up QEMU and Buildx'
+inputs:
+  GITHUB_TOKEN:
+    required: true
+outputs:
+  image-name:
+    value: ghcr.io/${{ steps.lowercaseRepo.outputs.lowercase }}:${{ github.ref_name }}-${{ env.SHORT_SHA }}
+  cache-name:
+    value: ghcr.io/${{ steps.lowercaseRepo.outputs.lowercase }}:cache
+runs:
+  using: "composite"
+  steps:
+    - name: Remove unnecessary files
+      run: |
+        sudo rm -rf /usr/share/dotnet
+        sudo rm -rf /usr/local/lib/android
+        sudo rm -rf /opt/ghc
+      shell: bash
+    - id: lowercaseRepo
+      uses: ASzc/change-string-case-action@v5
+      with:
+        string: ${{ github.repository }}
+    - name: Set up QEMU
+      uses: docker/setup-qemu-action@v2
+    - name: Set up Docker Buildx
+      uses: docker/setup-buildx-action@v2
+    - name: Log in to the Container registry
+      uses: docker/login-action@465a07811f14bebb1938fbed4728c6a1ff8901fc
+      with:
+        registry: ghcr.io
+        username: ${{ github.actor }}
+        password: ${{ inputs.GITHUB_TOKEN }}
+    - name: Create version file
+      run: make version
+      shell: bash
+    - name: Create short sha
+      run: echo "SHORT_SHA=${GITHUB_SHA::7}" >> $GITHUB_ENV
+      shell: bash