[import-w3c-tests] Be stricter about argument parsing

[gsnedders]

b696c86

[import-w3c-tests] Be stricter about argument parsing
https://bugs.webkit.org/show_bug.cgi?id=259750
rdar://problem/113293027

Reviewed by Jonathan Bedard.

This moves us to using argparse.ArgumentParser.parse_args instead of
argparse.ArgumentParser.parse_known_args, thereby resulting in unknown
arguments causing an error.

Additionally, add an error when you pass a test_path that doesn't
start with web-platform-test/, as this is practically required.

* Tools/Scripts/webkitpy/w3c/test_importer.py:
(TestImporter.do_import):
* Tools/Scripts/webkitpy/w3c/test_importer_unittest.py:

Canonical link: https://commits.webkit.org/266587@main

2556334

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
❌ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🛠 gtk
✅ 🧪 webkitpy	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🧪 gtk-wk2
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🧪 api-gtk
	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2
	✅ 🛠 tv-sim
	✅ 🛠 watch
✅ 🛠 🧪 unsafe-merge	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash a45997a)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	⏳ 🛠 wincairo
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	🧪 wpe-wk2
✅ 🧪 webkitperl	🧪 ios-wk2	🧪 api-mac	✅ 🛠 gtk
✅ 🧪 webkitpy	⏳ 🧪 ios-wk2-wpt	🧪 mac-wk1	🧪 gtk-wk2
⏳ 🛠 🧪 jsc	🧪 api-ios	🧪 mac-wk2	🧪 api-gtk
	⏳ 🛠 tv	✅ 🧪 mac-AS-debug-wk2
	⏳ 🛠 tv-sim
	⏳ 🛠 watch
	⏳ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on current version of this PR (hash 2556334)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
❌ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🛠 gtk
✅ 🧪 webkitpy	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🧪 gtk-wk2
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🧪 api-gtk
	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2
	✅ 🛠 tv-sim
	✅ 🛠 watch
✅ 🛠 🧪 unsafe-merge	✅ 🛠 watch-sim

[gsnedders]

(code style violation is deliberate to match local style, without reformatting quite a lot more)

[webkit-commit-queue]

Committed 266587@main (b696c86): https://commits.webkit.org/266587@main

Reviewed commits have been landed. Closing PR #16331 and removing active labels.