tests,stdlib: Add test to check gem5-resources downloading

This test ensures all the resources in resources.json can be downloaded
and that their md5 values are valid. This has been set as a
very-long/weekly test as downloading all the resources is costly.

Change-Id: Ia574d0a9610849af3653fc742acb214ea7496767
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/59771
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
3 files changed