Add support for chunked uploads

Breaking changes:

The getPathFromServerId no longer returns the full path to the file. Instead it returns the "disk"-local path.
For example:

// Before
/var/www/html/public/storage/filepond/yourFile.jpg
// After
filepond/yourFile.jpg

You have to use Laravel's storage class to access the files now:

$filepond = app(Filepond::class);
$disk = config('filepond.temporary_files_disk');

$filePath = $filepond->getPathFromServerId($serverId);
Storage::disk($disk)->get($filePath); // This returns the file contents as a string