[canvaskit] Add test harness for running all gms and getting output

The JS starts a web server and then uses puppeteer to load the html
page. The page will load the compiled JS+WASM to run the GMs,
calculate the md5 hash of the pixels using the exact same algorithm
as DM and then get those encoded as a PNG. The HTML then makes
a post request with that image data (assuming it's not an image we
have seen before) and keeps all the test results in a simple
JSON array.

The JSON array will be read in by a task driver in a followup CL.

Bug: skia:10812
Change-Id: I90e8ed42bd96ae11fa75ce84ef2ee1a97ab93d5f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/328378
Reviewed-by: Leandro Lovisolo <lovisolo@google.com>
4 files changed