dart:io on Windows cannot access certificates in the machine store

[dnfield]

See

sdk/runtime/bin/security_context_win.cc

Lines 52 to 55 in 29c850d

	// Open root system store.
	// Note that only current user certificates are accessible using this method,
	// not the local machine store.
	HCERTSTORE cert_store = CertOpenSystemStore(NULL, L"ROOT");

This can cause issues for Windows users who have certificates installed at the machine level that would satisfy TLS/SSL needs, even if they do not have them installed in the user store.

If we used CertOpenStore we could also access machine level certificates.

/cc @aam

[zanderso]

It would also be useful for debugging if the command line VM took a flag to skip the native platform trusted root certs and only use the compiled-in certs on the platforms where they are compiled in. I'll file a separate issue for that.

[zanderso]

I filed #45912