feat: Support non JSON (aka binary) fetches

[ntucker]

Fixes #266.

Motivation

With Rest Hooks already useful for JSON type data, it should allow for other response types like images, ArrayBuffers, etc.

Solution

Sample FetchShape:

export const photoShape = {
  type: 'read' as const,
  schema: null as ArrayBuffer | null,
  getFetchKey({ userId }: { userId: string }) {
    return `/users/${userId}/photo`;
  },
  fetch: async ({ userId }: { userId: string }) => {
    const response = await fetch(`/users/${userId}/photo`);
    const photoArrayBuffer = await response.arrayBuffer();

    return photoArrayBuffer;
  },
};

Usage:

const photo = useResource(photoShape, { userId });

Open questions

useResource() ensures a response, but we're still stuck with the | null union. This is needed however to have sane defaults. Currently the only distinction is based on entities, which this cannot be so would require some rethinking from normalizr design.

Perhaps a better solution is to simply allow schema to be undefined, and then take the return type of fetch.

[kmartinezmedia]

Nice! This is a great feature!