feat: allow sorting sent files

[Jean-Beru]

As mentionned in gotenberg/gotenberg#1498 by @jordy-manner, it's not possible to sort sent files.

We could add a method to change the filename in the form data (not the file itself, ex: --form 'files=@portrait.pdf;filename=01-portrait.pdf') in order to respect calls order. Example:

$builder
    ->files('c.pdf', 'a.pdf', 'b.pdf', 'a.pdf')
    ->sortFilesByName() // Default behavior => a, a, b, c
    ->sortFilesByCall() // Files are renamed => c, a, b, a

It will concern the Merge endpoint, maybe the Embed once (not sure).