Move ArchiveTar to composer

Problem/Motivation

ArchiveTar is a code from another project in core/lib/Drupal/Core/Archiver/ArchiveTar.php - but we can get it from composer now - see https://packagist.org/packages/pear/archive_tar

Proposed resolution

Do it and alias the core class to the vendor version and deprecate the core class.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet