[DC] Reject non-JSON-serializable credential data

Introduce IsSerializable helper that wraps v8::JSON::Stringify in a
TryCatch, detecting values that cannot be JSON-stringified (e.g.
BigInt objects or circular references).

Before converting requests to Mojo types, discovery and creation now
early-reject with a TypeError and clear error message when serialization
fails.

Symbol does not throw on JSON.stringify, so it is excluded from this
patch's tests; Symbol support will be added in a future patch.

Bug: 427885787
Change-Id: I90b691a9e6431d6fe58dbd32e36c2c91772606f9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6772545
Commit-Queue: Suyeon Ji <zeesuyeon@gmail.com>
Commit-Queue: Mohamed Amir Yosef <mamir@chromium.org>
Reviewed-by: Jinho Bang <zino@chromium.org>
Reviewed-by: Mohamed Amir Yosef <mamir@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1494222}