DataStore extension

Allow storing data, somehow like this:

```
interface MyData {
  id: string
  name: string
}

const db = new DataStore<MyData>()
const obj = await db.put(someObject)
const someObject = await db.get(obj.id)
await db.list()
await db.delete(obj.id)
```

Needs some prototyping what part of this should live in Deno or Rust land