core(lib): add chrome-extension to URL allowedProtocols and add test

[justinribeiro]

Resolves #6421.

[patrickhulce]

I think auditing chrome extensions from the Chrome extension still won't work, but it'd be too much of a pain IMO to thread that environment bit down of DT vs. extension here. LGTM!

[brendankenny]

yeah, agreed. We need to fix the extension offering to auto-open a github issue on INVALID_URL anyways, so we can fix the problem then if it starts popping up through a different exception path.