inspector: use js_app.html as the landing page for chrome devtools

As of this commit in chromium -
https://chromium-review.googlesource.com/c/chromium/src/+/905450
a new landing page (js_app.html) has been added and inspector.html
has been made as the fallback page.

Another motivation for this patch is the following bug in
chromium -
https://bugs.chromium.org/p/chromium/issues/detail?id=846642
due to which, source maps won't get applied with inspector.html,
but works with js_app.html

In order to maintain compatibility, this patch adds a URL
"devtoolsFrontendUrlCompat" to the response of /json/list REST API
so that those using Chrome browsers older than 66.0.3345.0
could use this to open DevTools.

PR-URL: https://github.com/nodejs/node/pull/21385
Refs: https://bugs.chromium.org/p/chromium/issues/detail?id=846642
Refs: https://chromium-review.googlesource.com/c/chromium/src/+/905450


Reviewed-By: Aleksei Koziatinskii <ak239spb@gmail.com>
Reviewed-By: Jan Krems <jan.krems@gmail.com>
Reviewed-By: Matheus Marchini <matheus@sthima.com>