Create port for new php-composer 2.x branch. (repocopied from
php-composer)

This new version includes optimizations for ram usage and a notable
speedup.

If you still need the old 1.x version for compatibility reasons
that's available in the devel/php-composer port.

upstream announcement: https://blog.packagist.com/composer-2-0-is-now-available/

Set same maintainer of php-composer at his request

PR: 252018
Approved by: Naram Qashat <cyberbotx@cyberbotx.com> (maintainer)