validate-imports is missing a whitelist entry for moduleForModel

While writing a model test I ran into this error:

```
Running "validate-imports:tests" (validate-imports) task
>> appkit/tests/unit/models/page-test: Cannot find "moduleForModel" export for "ember-qunit"

Warning: Validation errors found in modules. Use --force to continue.

Aborted due to warnings.
    Warning:  Use --force to continue.
        
        Aborted due to warnings.
```

Adding moduleForModel to the whitelist seems to fix it.