Rename the required .well-known/first-party-set to include a .json extension

[sjledoux]

Don Marti from CafeMedia brought to our attention that individuals relying on legacy web servers, shared hosting, or a variety of other hosting plans who want to add their proposed First-Party Set to the Github repository at github.com/GoogleChrome/first-party-sets may have difficulty serving an extensionless JSON file such as the currently required .well-known/first-party-set.

Currently, adding a .json extension to the name of the file would cause their First-Party Set to fail the checks on the repository, putting these individuals at a disadvantage. The requirements should be modified so that FPS submitters must have their sites' JSON files served at .well-known/first-party-set.json so that all submitters can more easily pass the checks.

[krgovind]

Thanks for the feedback, @dmarti!

This seems like a reasonable change to make; ideally in advance of accepting new "live" submissions intended to be applied to Chrome M113+ (which is the milestone we hope to ship FPS in Chrome).

[jeremyroman]

We had a similar discussion for another .well-known URL (buettner/private-prefetch-proxy#16 and links from there), which might be of interest.

[dmarti]

My comment was based on a related issue, from the Global Privacy Control site: w3c/gpc#9 (The IAB's sellers.json file requires less web server admin work to support)

[sjledoux]

Thank you for the link @jeremyroman. I think with the cases mentioned in the gpc-spec and those in private prefetch proxy, we will proceed with modifying the checks in github.com/GoogleChrome/first-party-sets to instead look for the .well-known at /.well-known/first-party-set.json.