feat: add check_previous_channel_release composite action

[duckhawk]

Summary

• Adds a new composite action check_previous_channel_release that verifies the previous release channel exposes the same module tag before promoting to the next channel.
• Action lifts the logic previously duplicated as .github/check_previous_channel_release.sh in module repositories (e.g. csi-ceph).
• Improves the version.json parser so it handles both single-line ({"version":"v0.1.14"}) and pretty-printed multi-line output from yq -o=json (newlines and indentation around the keys), via a multiline-aware PCRE grep (grep -aoPz).
• Updates README.md to list the new action.

Usage example

- uses: deckhouse/modules-actions/setup@v14
  with:
    registry: ${{ vars.PROD_REGISTRY }}
    registry_login: ${{ vars.PROD_MODULES_REGISTRY_LOGIN }}
    registry_password: ${{ secrets.PROD_MODULES_REGISTRY_PASSWORD }}

- uses: deckhouse/modules-actions/check_previous_channel_release@v14
  with:
    module_source: "${{ vars.PROD_REGISTRY }}/${{ vars.PROD_MODULE_SOURCE_NAME }}/ce/modules"
    module_name: ${{ vars.MODULE_NAME }}
    module_tag: ${{ github.event.inputs.tag }}
    release_channel: ${{ github.event.inputs.channel }}
    registry: ${{ vars.PROD_REGISTRY }}
    registry_login: license-token
    registry_password: ${{ secrets.PROD_MODULES_READ_REGISTRY_PASSWORD }}

Test plan

• Locally verified the new grep -aoPz '\{\s*"version"\s*:\s*"[^"]+"\s*\}' | head -z -n 1 | tr -d '\0' | jq -r .version pipeline against:
  • {"version":"v0.1.14"}
  • pretty-printed {\n "version": "v0.1.0"\n}
  • the same JSON embedded in a binary stream with NUL/non-UTF-8 bytes around it
• Smoke-test by wiring a module repo (e.g. csi-ceph deploy_prod.yml) to check_previous_channel_release@v14 and triggering a non-alpha channel deploy.