[C++] Delimit JSON documents without parsing them #51470

Describe the enhancement requested

simdjson has a multi-stage parser that first finds structural elements in the entire buffer (including document boundaries). Only the second stage, which is lazy, actually need to parse the documents.

Similarily parse_many already computes all document boundaries and we can iterate its output to consume the documents without parsing any documents:
https://github.com/simdjson/simdjson/blob/6913ee1a17a57d23a2e9f458d8e04e96cd43ecab/doc/parse_many.md?plain=1#L85-L88

Component(s)

C++