Add a sniff for dynamic keys passed to get_block_wrapper_attributes

### Description

Keys provided to the `get_block_wrapper_attributes` function are turned into attribute names, and are not escaped. That's fine if we're specifying a hardcoded value and that hardcoded value is known to be safe, like:

```php
echo get_block_wrapper_attributes( [ 'data-my-key' => $my_value ] );
```

Values are already escaped via `esc_attr` in `get_block_wrapper_attributes`, so dynamic values are okay there.

However, if there is a dynamic key, like:

```php
$attributes[ $my_key ] = $my_value;
echo get_block_wrapper_attributes( $attributes );
```

We should flag that, because the key is dynamic and isn't escaped. Escaping should be done by `sanitize_key`.

### Use Case

When a user uses the `get_block_wrapper_attributes` function, phpcs should throw an error if the user has a dynamic key that is unescaped.