Deprecated archiver procedural functions

Procedural functions archiver_get_extensions() and archiver_get_archiver() are deprecated. Instead, the plugin.manager.archiver exposed two news methods ::getExtensions() and ::getInstance() respectively.

Before:

$extensions = archiver_get_extensions();
$archiver = archiver_get_archiver($file);

After:

$extensions = \Drupal::service('plugin.manager.archiver')->getExtensions();
$archiver = \Drupal::service('plugin.manager.archiver')->getInstance([
   // Archiver objects require a real path to a local file, not a file stream.
   'filepath' => \Drupal::service('file_system')->realpath($file),
]);