provide json endpoint with combined results

I'd love to get a single json endpoint that provides a combined array of all latest results which is exposed via the service or nginx. This json should provide the pkgctl version check --json results which would allow the pkgctl tooling to use our central service and have results for packagers instantaneously (we would provide a devtools option to run locally as well, which this service would be calling in the future). This deduplicates checks against upstream locations and gives packagers instant results, which would be an amazing user experience.

It would be perfect if the combined result is an object where the key is the pkgbase and the content is the json result from pkgctl, this would allow the caller to access individual slots quite efficiently instead of O(n). The estimated size of the combined result is around 2.4M uncompressed and less than 1M gzip compressed (by the webserver), which is reasonably small.