Pass the config schema to adapters

[dirkluijk]

This allows adapters to transform the source object to match the schema, see #22.

For example:

type Adapter<T extends z.AnyZodObject = z.AnyZodObject> = {
  read: (schema: T) => Promise<z.infer<T>>;
  // ...
};

The benefit is that for a custom adapter, you won't need to pass the schema to it every time you create it.

Since adapters may as well ignore this argument, this would be a backwards compatible change.

[dirkluijk]

I opened this issue specifically for #22, but I suggest to first explore some directions in that issue. ;)