Support for dynamic injection of /docs folder into Dockerfile and MRO label support

[clemensutschig]

Is your feature request related to a problem? Please describe.

1. If we want to inject metadata into the image - we only have labels, and we generate already a file that we stick into the docker context (https://github.com/opendevstack/ods-jenkins-shared-library/blob/master/src/org/ods/component/BuildOpenShiftImageStage.groovy#L30)
   In order for it to be visible in the image one needs to add a COPY directive into the docker file -> touch every quickstarter. And if we want to add more - touch again.

2. If we want to add extension image labels - there is already a feature called imageLabels (https://github.com/opendevstack/ods-jenkins-shared-library/blob/master/src/org/ods/component/BuildOpenShiftImageStage.groovy#L11) but this is not useful if we call the shared lib from load in the MRO..

Describe the solution you'd like

1. Inject the copy line into the docker file during build
2. In case environment variable exist, named ods.build.XXXX add them into the imageLabels

Describe alternatives you've considered
there is non, except for (1) touching all quickstarters.