This abstraction layer was not useful, so it is removed to simplify the
API around `ClassDefinition`.
A new method `ClassDefinition::type()` is also added, giving access to
the `ClassType` instance when working with a class definition.
Integer range can be used as follows:
```php
final class SomeClass
{
/** @var int<42, 1337> */
public int $intRange; // accepts any int between 42 and 1337
/** @var int<-1337, 1337> */
public int $negativeIntRange; // also works with negative values
/** @var int<min, 1337> */
public int $minIntRange; // `min` can be used…
/** @var int<0, max> */
public int $maxIntRange; // …as well as `max`
}
```
Note that `min` and `max` will check the range with PHP's internal
constants `PHP_INT_MIN` and `PHP_INT_MAX`.
