src: add /json/protocol endpoint to inspector

Embed the compressed and minified protocol.json from the bundled
v8_inspector and make it available through the /json/protocol endpoint.

Refs: https://github.com/nodejs/diagnostics/issues/52
PR-URL: https://github.com/nodejs/node/pull/7491


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>