[RFC0028] Implement Cloud Native Buildpacks lifecycle

[pbusko]

• A short explanation of the proposed change:

Implementation of the RFC-0028

• An explanation of the use cases your change solves

This PR adds third lifecycle option: cnb. This lifecycle type utilises Cloud Native Buildpacks to produce droplets.

• Links to any other associated PRs

https://github.com/cloudfoundry/community/blob/main/toc/rfc/rfc-0028-cnb-lifecycle.md

• [X] I have reviewed the contributing guide

• [X] I have viewed, signed, and submitted the Contributor License Agreement

• [X] I have made this pull request to the main branch

• [X] I have run all the unit tests using bundle exec rake

• [X] I have run CF Acceptance Tests