Populate `entryPoints` from `deno.json#exports` or `jsr.json#exports`

[rotu]

Exports are already declared in deno.json and/or jsr.json, but are required in BuildOptions. It would be nice if build() generated the entry points list.

This is what I have in my build script to do the same:

import { build } from "@deno/dnt"
import denojson from "../deno.json" with { type: "json" }

await build({
  //...
  entryPoints: Object.entries(denojson.exports).map(([name, path]) => ({
    name,
    path,
  })),
  //...
})