To ensure that things are built we need to update the modification time
on the files we download. This adds a script to download the requested
files and then touch everything that was downloaded in the traces
folders.

Bug: chromium:1096577
Change-Id: Idce6abb6100e7c662429a9db71b1a44a78dd88a6
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2252544Reviewed-by: Cody Northrop <cnorthrop@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Courtney Goeltzenleuchter <courtneygo@google.com>