the solution as described by benjyw is working, my dir structure now looks like this

3rdparty/go/golang.org/x/text/BUILD

in this build file i have

go_remote_library(pkg="unicode/norm",
  rev='3bd178b88a8180be2df394a1fbb81313916f0e7b',
)

go_remote_library(pkg="transform",
  rev='8bf377e291b5e40c0e6bd1b8e139f4ba31e87a21',
)

Thanks for the help guys