Merge latest upstream main changes

Summary:
- Better CLI arguments parsing
- Builtin compression support for large source files

Change-Id: Ia0bf37ae5405adb218a2da2c072a1f9cf0ee9f95
Reviewed-on: https://chromium-review.googlesource.com/c/external/github.com/WebKit/JetStream/+/7021129
Reviewed-by: Marja Hölttä <marja@chromium.org>