extend pipeline operator with PipelineTemplate resource

[pauldougan]

What

Create a higher order PipelineTemplate CRD for the concourse operator that can be referenced/utilized from the Pipeline kind

Why

So we can define reusable common pipelines (such a "build a docker image from repo x" and "apply the kubeyaml in repo x to namespace y")

The short term goal is to enable us to create a drop-in replacement for the FluxHelmRelease driven by concourse

It's done when

• We are able to create a PipelineTemplate resource
• We can create a Pipeline that specifies and PipelineTemplate and values and results in a pipeline being set in concourse

[chrisfarms]

WONTFIX ... this is unlikely to be proiotised as is