Saves the W3C XML Schema Test Suite (2006-11-06) in the repo as the
complete, unmodified xsts-2007-06-20.tar.gz (4.4 MB), the only form the
W3C Document License permits redistributing. The extracted 39,399 files
are still never committed (that would be a modified redistribution).
A README records the provenance, SHA-256, and license. scripts/fetch-xsts.sh
now extracts this vendored archive when present (no network) and only
downloads as a fallback. The archive is excluded from the test bundle in
Package.swift since the runner reads it off disk via XSTS_ROOT, not from
resources.
Mihaela Mihaljevic
925172cd84