cmd/go: convert testCDAndGOPATHAreDifferent to the script framework

cmd/go: convert testCDAndGOPATHAreDifferent to the script framework

This is a bit complex. There's a driver program to run go with modifications
to the GOPATH used to test Windows.

Also remove the cd method on testgoData, because this was the last function
that used it.

Part of converting all tests to script framework to improve
test parallelism.

Updates #36320
Updates #17751

Change-Id: I3e8e27f37fd3701bd36b6365b128dd73b69181c0
Reviewed-on: https://go-review.googlesource.com/c/go/+/214578
Reviewed-by: Jay Conrod <jayconrod@google.com>