Add role helper for user model

Add role checker for user model.

```php
$user = User::find(1);

$user->is('foo'); //check if user has the specified role
$user->isAny(['foo', 'bar']); //check if user has at least one of the roles

$user->isNot('foo'); //check if user does not has the specified role
$user->isNotAny(['foo', 'bar']); //check if user does not has at lease one of the roles
```

Signed-off-by: ahmadshah <ahmadshahhafizan@gmail.com>