This adds a DCHECK into v8-inspector-session-impl.cc, covering what
we previously checked within ConvertCBORToJSON.

Upstream reviews:

"Separate the lightweight check for CBOR messages from ParseCBOR."
https://chromium-review.googlesource.com/c/deps/inspector_protocol/+/2001536

"Remove Exported::writeBinary."
https://chromium-review.googlesource.com/c/deps/inspector_protocol/+/2005797

New Rev: ac6919eb836521a96cc18931f0bf270d8c1b53a1

Change-Id: I52076a8f77b27c24c3afb35c40afbbe94e0ca05c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2002935Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Commit-Queue: Johannes Henkel <johannes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65854}