Use simdjson in JSONParser

[joyeecheung]

JSONParser predated the inclusion of simdjson, we were using the V8 JSON parser for convenience but it requires more than it needs to do the job (e.g. then the parser cannot be used to parse configs before V8 is initialized, then there's a chicken-and-egg problem if we want to use that to configure how to initialize V8).

node/src/json_parser.h

Lines 28 to 30 in ce8f085

	// We might want a lighter-weight JSON parser for this use case. But for now
	// using V8 is good enough.
	RAIIIsolateWithoutEntering isolate_;

It would be simpler to just use simdjson to do this now that we have it.

[joyeecheung]

As I was reviewing #59308 I noticed that the best way to migrate is to just ditch the current JSONParser interface since that is based on random access. It's better to just use simdjson directly wherever JSONParser is currently used if the caller needs to parse fields of random order as the simdjson documentation recommend to do so by iterating over the fields in a loop, see #59308 (comment)