type using not implements clause.Interface

## Describe the feature

type using not implements clause.Interface, I want to add the 'Name() string' method
```
// Name implements clause.Interface interface
func (u using) Name() string {
	return usingName
}

// MergeClause implements clause.Interface interface
func (u using) MergeClause(*clause.Clause){}
```

## Motivation 

## Related Issues 
