Support URL preservation for partial reload requests to API routes

[nathanmedz]

As far as I can tell, if you make a request to a url that is not your current url there is currently no way to prevent Inertia from modifying the browser url when you receive a response, even if your response renders the same component. With partial renders, this would mean that you can use API endpoints to fetch/ modify part of the data on your page without a full data reload. This is especially useful for pages with primary data that is expensive to fetch and secondary data that is frequently edited.

Example - making a request from something like https://mysite.com/home,

router.post(`/some_api_route`, data, {only: ['partial_data']})

this will partially reload the data as expected, but will also modify the browser url to https://mysite.com/some_api_route which is undesirable in many cases

[Tivixo]

Maybe this could help: #1009

But it doesn't work, I ask here about it: #1702
Please tell me if you find out how to use it.