OS images: use "ref", "stream" and "version"

Switch azure default region to west us
Update find-image script to work with new API spec
Add version for every os image build
generate measurements: Use new API paths
CLI: config fetch measurements: Use image short versions to fetch measurements
CLI: allows shortnames to specify image in config
Image build pipeline: Change paths to contain "ref" and "stream"

.github/workflows/update-cli-reference.yml

@@ -36,7 +36,7 @@ jobs:
       - name: Check if action branch exists
         run: |
           ex="$(git ls-remote --heads origin action/constellation/update-cli-reference)"
-          echo "EXISTS=$(if [ -z "$ex" ]; then echo 0; else echo 1; fi)" >> "$GITHUB_ENV"
+          echo "EXISTS=$(if [[ -z "$ex" ]]; then echo 0; else echo 1; fi)" >> "$GITHUB_ENV"
 
       - name: Publish new reference (create new branch)
         if: ${{ env.EXISTS == 0 }}