feat: key on request destination

[dsherret]

This is for Deno 2.0. We need to slightly break the cache and key on the request destination in addition to the specifier.

This is to better support import attributes. For example, scenarios like the following couldn't be represented in the cache until now:

import value from "https://example.com/data";
import value from "https://example.com/data" with { type: "json" };

In Deno itself, we're going to error for scenarios like this, but we need to allow multiple programs to use scenarios like this independently.

Waiting on:

• Deno graph changes to support this.