Fundraising: privatebin image

This is the software we're using to offer donors their own data when they request it under privacy laws.

Pretty bare-bones, maybe could get away with just using fundraising-civicrm-buster-php73-apache2, but this gives us the same central logging and xdebug configurability we have on other fundraising images.

Bug: T285881 Change-Id: I1ccd58e4f7699cacc037f441452122f5eabfad43