Move search artifacts in html step

[stsewd]

This together with readthedocs/readthedocs-sphinx-ext#43 closes #3393.

Still wip, I need to remove the previous json builder, and update the rtd extension.

[stsewd]

I think this is kind of ready for a review, for test locally you need to replace this line https://github.com/stsewd/readthedocs.org/blob/ffe2d55c15bb8766e00ace3bad693f1b649ecf57/readthedocs/doc_builder/python_environments.py#L249-L249 for git+https://github.com/stsewd/readthedocs-sphinx-ext.git@add-json-process

If what I'm doing is fine, probably we'll need to remove all the search args from the methods (neither mkdocs uses this #4205)

I'm having doubts with readthedocs/readthedocs-sphinx-ext#43 (comment), also I'm not very sure how to test this (it is already tested in the other repo), I suppose I can test that the _json dir is ignored atleast.

[ericholscher]

This looks like a good PR for closing out the JSON stuff. I do think we should probably take a staged approach to deploying, which looks like:

• Ship the JSON output in the extension with a config option to enable it
• Ship the .org with a feature flag that turns on the JSON extension output config & disables the normal JSON builder
• Test this with a few projects w/ the feature flag, scaling things up and monitoring the logs to see if this makes things explode
• Eventually scale the feature flag up to all projects
• Then remove the existing JSON builder & integration into RTD for it

[stsewd]

Ok. got it. I'll see if this PR can be reused or making a new one makes sense.

[stsewd]

Ok, closing this PR most of the changes aren't necessary with the new decision.