deps: update v8_inspector

To add a LICENSE file along with the v8_inspector code, we need to
pick up v8_inspector from an intermediate repository:
https://github.com/pavelfeldman/v8_inspector. This repo still tracks
upstream code in Blink.

This roll also picks up the latest v8_inspector from upstream fixing
a few issues.

* Pickup commit id bc60957 from pavelfeldman/v8_inspector
* Update node.gyp to adapt to the new file paths
* Update the DevTools hash for the devtools frontend.

Fixes: #7123
Fixes: #7736
Fixes: #7734
PR-URL: #7796
Reviewed-By: bnoordhuis - Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: jasnell - James M Snell <jasnell@gmail.com>

Author: ofrobots