build-system: Add more integration tests

These scripts add a new testing infrastructure designed to
simulate a Vanilla Ubuntu installation and install
various packages to test how well our PPA packages install.

It can also be used to extract valuable data such as an
up to date dependency graph and the full build dependency
list. See the sflphone_integration.sh script for examples.

More tests will come later on.

Refs: #51915

Change-Id: I7819b338cbbbacae3e93f2a1fc9b9fb3e3537db9