Test feature view dummy entity serialization after apply()

## Expected Behavior 
Test feature view dummy entity serialization after apply()

```python
assert FeatureView.entity_columns == [] 
# run apply
assert FeatureViewFromRegistry.entity_columns[0].name == DUMMY_ENTITY_ID
```

## Current Behavior
No tests

## Steps to reproduce
N/A

### Specifications
N/A

## Possible Solution
Add test