Convert `_json` to Argument Clinic

[AA-Turner]

Proposal:

As discussed in #137630 (comment), for @hnnynh at the PyCon Korea sprints

cc @corona10

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Linked PRs

• GH-137821: Convert _json to use Argument Clinic #138869
• gh-137821: Convert _json module to use Argument Clinic #140778
• gh-137821: Improve Argument Clinic definitions in the _json module #140780
• [3.13] gh-137821: Fix wrongly tested json.decoder.scanstring #140781
• [3.14] gh-137821: Fix wrongly tested json.decoder.scanstring #140782

[corona10]

@hnnynh plan to take a look at this issue :)

Thank you for all your support @AA-Turner !

[picnixz]

What about performance? AC induces a slight overhead so we should be careful about it. cc @serhiy-storchaka

[AA-Turner]

Yep, I would expect the PR to run the JSON benchmarks.

[picnixz]

We also need macro benchmarks

[corona10]

Yoonho Hann, please consider writing a benchmark script using pyperf or timeit. But please write a draft PR first :)

[corona10]

Plan to directly mentor her for this issue.

[hnnynh]

Sorry for the delay in sharing. It took me a little while to understand what needed to be done.
I received guidance from @corona10 on how to start the work (two commit links below) and was able to plan my tasks.

corona10@fe54046
corona10@d4ca8d3

I'll aim to submit a PR by next week.