Create autopkgtest for unix-privesc-check

It appears that unix-privesc-check does not have any automated runtime tests, and is currently missing on autopkgtest.kali.org. As an effort to increase our coverage to allow for more automated package testing please could a non-superficial test (or more!) be created.

For more information on creating tests, can be found here Contributing run-time tests with autopkgtest, as well as on a example package guide.

This package is in our kali-linux-headless metapackage.