Makes future development easier.
New features:
* A more compact and cleaner results view
* Concurrent testing, much quicker across multiple cores
* Supports comparing output against an expected file, including a text diff of differences. Also has a flag for updating the expected outputs
* Advanced file-globbing support, including scanning for files in subdirectories
* Skip lists are now no longer hidden away in the tool, but defined as a SKIP header in the *.expected.* file
Change-Id: I4fac80bb084a720ec9a307b4acf9f73792973a1d
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/50903
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: David Neto <dneto@google.com>