refactored build process for che server, dashboard, and ws loader

Because nothing in Che ever stays static very long, the process for building the Che Server as a monolithic maven build is changing in 7.13.

Therefore where there was Che dev, Che parent+depmgmt and Che server repos to build in https://codeready-workspaces-jenkins.rhev-ci-vms.eng.rdu2.redhat.com/job/crw_master/ for CRW 2.1, in 2.2 we will instead need:

• Che dev (maven)
• Che parent (maven)
• Che ws loader (ts docker build)
• Che dashboard (ts docker build)
• Che server (maven) + depmgmt (merged into root pom)

We could build the intermediate workspace loader and dashboard projects as images on RHEL8 in Brew, then use their artifacts to build Che server assembly.

But since the containers themselves are throwaway images, I think it's better to retool the crw_master build like this:

• Che dev (maven; stash pom for future stage)
• Che parent (maven; stash pom for future stage)
• Che ws loader (ts docker build; extract artifacts and stash for future stage)
• Che dashboard (ts docker build; extract artifacts and stash for the next stage)
• Che server (maven; collect stashed artifacts and assemble)
• push CRW assembly to Brew and use in server build
• no new intermediate / throwaway containers in Brew, Comet, or Quay