Similar to https://issues.redhat.com/browse/BUILD-1491

BuildConfigs can contain inline Dockerfiles
As an example: https://github.com/openshift/release/blob/0f8dec6a1d8b39d84356bee4afd25297b15dbfe0/clusters/app.ci/supplemental-ci-images/azure/base-images/test-base.yaml#L28

There currently does not seem to be support for defining inline Dockerfiles in Shipwright, however it is fairly trivial to do so:

Add a parameter

  - default: ""
    description: Dockerfile contents to use for build
    name: dockerfile-contents
    type: string

process it if it exists, and then write it to the Dockerfile location with something like:

      if [ "${dockerfileContents}" != "" ]; then
        echo "${dockerfileContents}"
        cat <<EOF >"${dockerfile}"
        ${dockerfileContents}
      EOF 
      fi  

This would make it easier to convert existing buildconfigs to shipwright builds.