distribution: add test to ensure pass-thru registry token is host-bound
distribution: add test to ensure pass-thru registry token is host-bound

Signed-off-by: Tibor Vass <3f1326dff4d85ad4ec938fb33f64575ace96db26@docker.com>

aditirajagopal/docker,aditirajagopal/docker,aditirajagopal/docker