Automatically change operator to `IN` for array values

Current, in order to use arrays, it has to manually change the operator to:
```php
$builder->where( [
    'ID' => [
        'operator' => 'IN',
        'value' => $array_value,
    ]
] )
```

Change it so it array is automatically detected, and the operator is set as IN when this happens:
```php
$builder->where( [
    'ID' => $array_value,
] )
```