move executable under cmd/stager

[#80943138]
move testrunner under cmd/stager
Use gunk workpool [#80393556]

Signed-off-by: Matthew Sykes <matthew.sykes@gmail.com>
wip

Signed-off-by: Nick Wade <nwade@pivotal.io>
wip-mjs

Signed-off-by: Nick Wade <nwade@pivotal.io>