ext,tests: Copy test's output files from /tmp to testing-results

ext,tests: Copy test's output files from /tmp to testing-results

When a test is complete, the output files are in a random folder
in /tmp.

This commit adds a procedure copying those files to
testing-results/SuiteUID/TestUID/ folder, where SuiteUID and
TestUID are the corresponding uid's of the test.

This procedure is triggered after a test is complete and before
the folder in /tmp being removed.

Change-Id: Id960e7f2f1629769008ae99aff4c8bfafa9ca849
Signed-off-by: Hoa Nguyen <hoanguyen@ucdavis.edu>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/33998
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>