Limit max size of `ConstantArrayType`

# Feature request

Adding the lines

```php
if (count($node->items) > 100) {
    $arrayBuilder->degradeToGeneralArray();
}
```

in https://github.com/phpstan/phpstan-src/blob/4d6904354ecd8df4f82e6b9b69925e4266d3f241/src/Analyser/MutatingScope.php#L1227

massively improves performance when handling large arrays

ref #1275
