Convert OCI Build Task to Prototype

[scottietremendous]

TLDR

• Simplifying the ability for Concourse to use a container image to build other container images utilizing Prototypes as opposed to the OCI Build Task.

Problem

• Currently, the oci-build-task is a container image that is meant to be used in a Concourse task to build other container images.
• The process to build an OCI image from its Dockerfile and push that image to a registry involves quite a lot of steps and can be verbose and complicated

Proposed Solution

• Utilize Prototypes instead! Given that prototypes is built off the back of resources, it should be an easier abstraction to reason about.

Outcomes

• OCI images become easier to build and push
• Users are provided the same flexibility and power, but in an easier to manage format

Current Status

• Blocked by ongoing initial prototypes work

References

#6540 - Add support for prototypes

See: Reinventing Resource Types