Add support for atomic updates

[kevinpiac]

Hey!

Thanks for this awesome library.

In the current version it seems it's not possible to update nested objects atomically.

Here is an example to illustrate what I mean.

Given the following schema:

interface User {
    firstName: string;
    metadata?: {
        nestedKey1?: number;
        nestedKey2?: boolean;
    }
}

If I want to update specifically one property inside the metadata object without replacing the whole object, I can do it by creating an atomic update object like this:

  const userId = db.users.id('my-id);

  // This works, but does not compile
  await db.users.update(userId, {
       "metadata.nestedKey1": 123
  });

It currently works fine, even using Typesaurus. However, the UpdateData type does not support it so it result in a compilation error.

I don't know if the best way would be to update the UpdateData type or to create a dedicated type but if you point me the right way to do it, I would be happy to submit a PR.