I identified some issues with the follow log:
```
[PHP] Warning: include(): Failed opening '<redacted>/apps/richdocuments/vendor/composer/../mikehaertl/php-pdftk/src/Pdf.php' for inclusion (include_path='<redacted>/3rdparty/pear/archive_tar:/<redacted>/3rdparty/pear/console_getopt:<redacted>/3rdparty/pear/pear-core-minimal/src:/<redacted>/3rdparty/pear/pear_exception:/<redacted>/apps') at /<redacted>/lib/composer/composer/ClassLoader.php#576
GET /ocs/v2.php/apps/libresign/api/v1/file/validate/file_id/2556
```
It's only occurr when use the app richdocuments, I saw that the package
mikehaertl/php-pdftk also is used by this app and because this the
autoload was mixed.
To solve this issue I used the package humbug/php-scoper that isolate
the dependency into a different namespace.
I also followed this article:
https://arthur-schiwon.de/isolating-nextcloud-app-dependencies-php-scoper
And the follow search results to see implementation examples:
https://github.com/search?q=OCA+path%3Ascoper.inc.php&type=codehttps://github.com/search?q=org%3Anextcloud+path%3Ascoper.inc.php&type=code
Considering that we already have tests to cover the usage of pdftk,
isn't necessary to add new tests, if the test pass, this change worked
fine because loaded the isolated packages and the isolated packages made
the necessary.
Signed-off-by: Vitor Mattos <1079143+vitormattos@users.noreply.github.com>
