Add URL Resolution that Fetches from a Table?

[theory]

By default, boon supports loading file: URLs via FileLoader, the only implementation of the UrlLoader trait. This is good because we wouldn't want to have HTTP code in the binary. And jsonschema doesn't even use the file loader, but loads schemas directly.

But it might be interesting to have some sort of UrlLoader implementation that knew how to read records from a table or view. I'm not sure what it would look like or how it would integrate into the existing functions. Perhaps we could add some GUCs that would be be used in new_compiler to configure a table-fetching URlLoader?

I don't know but it would be fun to play with some ideas and see if it's feasible or useful.