Add Shell Tests

[camillobruni]

Add support for running basic cli.js tests with npm run test:jsc, npm run test:spidermonkey, npm run test:v8

[camillobruni]

I think this is now working...
We probably still want to add some additional validation at some point (especially for the web versions of these workloads),

[camillobruni]

Going to skip JSC for now, since we get a "rate limit exceeded" warning from querying the amazon buckets... not sure if there is an easier way to install this. I presume we can enable this again after a while and caching will prevent us from breakage.

[kmiller68]

Fun fact jsc exists on Mac but it's not part of the default PATH. You can run it from /System/Library/Frameworks/JavaScriptCore.framework/Versions/Current/Helpers/jsc. I think it moved at some point but that was a few years ago so that path should be fine.

[camillobruni]

ah cool, ok, I'll add a macos check and use that as the default ther, keeping jsvu as backup for other platforms.