Add Helper Functions for ResourceMeta

| Q                | A
| ---------------- | -----
| Bug report?      | no
| Feature request? | yes
| BC Break report? | no
| RFC?             | no

things like

```
$resourceMetadata->withAttributes(['locale' => 'de']);

$resourceMetadata->withResourceId($id);
```

that just creates a clone of it, but with the changed attributes. Makes usage for normalizer a bit easier.