[Infra] Install visionOS sim in storage x spm workflow (#14579)

Author: ncooke3

.github/workflows/storage.yml

@@ -124,6 +124,9 @@ jobs:
       run: ls -l /Applications/Xcode*
     - name: Xcode
       run: sudo xcode-select -s /Applications/${{ matrix.xcode }}.app/Contents/Developer
+    - name: Install visionOS, if needed.
+      if: matrix.target == 'visionOS spm'
+      run: xcodebuild -downloadPlatform visionOS
     - name: Initialize xcodebuild
       run: scripts/setup_spm_tests.sh
     - name: Unit Tests