Starts the first request of the page a visit lands on before that page's
code has loaded, so that the two travel together rather than one after the
other. main.tsx starts it as the app boots (startLandingRequest),
and useAuth's authFetch hands its response to the page that asks for
the same URL (takeEarly), in place of a request of its own.
Usage
import * as mod from "src/utils/shared/earlyFetch.ts";