Add a cache mecanism

## Description

Since this library relies on [nikic/fast-route](https://github.com/nikic/FastRoute), we can leverage the cache feature.

## Expected behavior

To be able to specify wether to enable caching route or not.

```php
use Folded\enableRouteCache;
use Folded\disableRouteCache;

enableRouteCache();
disableRouteCache();
```

It should be disabled by default.

And being able to specify in which file to store the cache.

```php
setRouteCacheFilePath(__DIR__ . "/cache/routes/routes.php");
```

## Actual behavior

No way to enable/disable route cache, nor a way to set the route cache file.

## Notes