Draft: Add Renovate GitLab components

Summary

• Adds support for GitLab components.
• Replaces templates references in .gitlab-ci.yml with the new components.
• Adds new custom manager to update docker image references in the GitLab components.
• Closes #98.

Notes

• Currently, the existing pipeline templates are maintained separately.
  • If we wanted the templates to use the components, we either need to:
    1. Release the next update as a breaking change. Job-level variables have higher precedence than global, so users must migrate to CLI flags.
    2. Have the component variables be global-level initially, and make the breaking change at a future point in time.
• Once merged, project settings needs to be updated to set a component project as a catalog project.

Resources

• CI/CD components
• Use variables with include