Add release tagging process for site gantry to ci

[apburnes]

When we close a feature/fix/chore merge request into main, we want our production CI pipeline to create a release merge request using our release tooling.

Notes

• Use pages-pipeline-tasks release tasks
• See pages-core for inspiration

Acceptance Criteria

• Create a .cz.json config in the root. See pages-editor repo for inspiration
• Create a tag manually in Github (0.1.0)
• Deploy production CI with deploy-env = production
• On staging deployments, it should generate the commitizen PR with release notes and version updates
• When the release PR is merged, the production pipeline should create the git tag
• Just enable the release task to generate the git tag and release notes pull request