When the application runs in a development environment, the cache
implementation should be decorated with `FileWatchingCache` to prevent
invalid cache entries states, which can result in the library not
behaving as expected (missing property value, callable with outdated
signature, …).
```php
$cache = new \CuyZ\Valinor\Cache\FileSystemCache('path/to/cache-dir');
if ($isApplicationInDevelopmentEnvironment) {
$cache = new \CuyZ\Valinor\Cache\FileWatchingCache($cache);
}
(new \CuyZ\Valinor\MapperBuilder())
->withCache($cache)
->mapper()
->map(SomeClass::class, [/* … */]);
```
This behavior now forces to explicitly inject `FileWatchingCache`, when
it was done automatically before; but because it shouldn't be used in
a production environment, it will increase overall performance.
