Keep the existing method for compatibility, by converting
to json from CBOR using the inspector_protocol_encoding library,
via a v8 specific interface library that directs routines for
converting between strings and doubles to v8's implementations.

This change also brings in the encoding.h / encoding.cc files from the
upstream inspector_protocol project. The only modification here
are the header guards, and the namespace. I will fix roll.py to
make it so that we pick up future changes.

third_party/inspector_protocol/BUILD.gn is specific to v8, by necessity.
third_party/inspector_protocol/.clang-format is a copy of the upstream
file. If we don't put this, we'll find ourselves auto-formatting the roll,
which is annoying.

This is a reland of
https://chromium-review.googlesource.com/c/v8/v8/+/1590627 with the
only modification in the DEPS file; this time I'm including
third_party/inspector_protocol/encoding/encoding{.h,cc} in addition to
the relative include there. Not sure why this is needed but I'm hoping
it gets me past the presubmit which may resolve the include path
relative to the V8 base (the ../../third_party is needed for when V8 is
embedded into Chromium).

Change-Id: Ic76b2b5faa7e1cbdceb15aff3f369e9a303e3e85
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1593646Reviewed-by: Alexei Filippov <alph@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Commit-Queue: Johannes Henkel <johannes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61214}