Add integration tests for building image from jessie to sid
These integration tests test the full user scenario of
- creating a qemu img of the release with autopkgtest-build-qemu
- downloading source and binary package "hello"
- running the autopkgtests of hello against the created image via autopkgtest-virt-qemu
The test creates image for
- jessie
- stretch
- bullseye
- bookworm
- trixie
- sid
These autopkgtests can catch regressions such as these recent ones:
- https://bugs.debian.org/1099577 (failure on buster)
- https://bugs.debian.org/1099580 (failure on sid)
- https://bugs.debian.org/1099053 (build failure on sid)
de96a321 (building of jessie images failiing on deb822-only apt .sources on the host)
Edited by Lee Garrett