It was just saying the copy of file failed with `exit status 1`,
no much details for what's going wrong.
Combine the stderr and stdout and show those info will be easier
for us to fix the problem.
Signed-off-by: Dave Chen <dave.chen@arm.com>
Currently, there are some unit tests that are failing on Windows due to
various reasons:
- Windows file permissions do not work the same way as the Linux ones.
- cp does not exist on Windows, and xcopy should be used instead.
- Get-Item does not work for hidden files / folders like AppData, but
works if given the -Force flag.