Update from=builder to URN format urn:cnb:builder:[email protected]

[jromero]

Description

Currently pack supports --buildpack from=builder to include all the buildpacks from the builder image. Since RFC #37, we should now support the URN format:

• urn:cnb:builder - A reference to ALL the buildpacks in the builder.
• urn:cnb:builder:bp.id - A reference to a buildpack with id bp.id in the builder.
• urn:cnb:builder:[email protected] - A reference to a buildpack with id bp.id at the specific version bp.version.

Proposed solution

1. Implement support for URN for:
   • pack build --buildpack
   • Config files
2. Add a deprecation warning when from=builder is used.

Additional context