Update auto-build-image with CNB support

Merged Hordur Freyr Yngvason requested to merge update-auto-build-image-with-cnb-support into master

What does this MR do?

Updates auto-build-image with initial support for building Cloud Native Buildpacks using pack along with documentation for the new feature.

The support is opt-in behind a CI variable.

This is also marks the first use of the new image tag schema (see the v0.1.0 release notes for details)

Closes #212610 (closed)

See also #25954 (closed)

Screenshots

Does this MR meet the acceptance criteria?

Conformity

Availability and Testing

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

  • [-] Label as security and @ mention @gitlab-com/gl-security/appsec
  • [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
  • [-] Security reports checked/validated by a reviewer from the AppSec team
Edited by Hordur Freyr Yngvason