Switch to debian repos, docker-compose workaround, add docker_users task

[niklassc-xyz]

Repo
Since Debian 10, docker is available in the Debian repos, so I switched the installation to this repository. It is important to remove the old docker-repo before installing this docker version.

Docker compose
I added an option to install docker-compose as well. As mentioned in the readme, this pulls a broken dependency which breaks part of the functionality of docker. The workaround of installing pass and gnupg2 fixes these though.
(https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=910823)

docker_users
This PR also adds a task with which docker-users can be added by putting them in the list docker_users.

[uubk]

Repo
Since Debian 10, docker is available in the Debian repos, so I switched the installation to this repository. It is important to remove the old docker-repo before installing this docker version.

Please don't do that, especially not as a default. Debian is fixed at Docker 18.09.1 (plus backported security patches), whereas upstream docker is at 20.10. AFAIU Debian is currently missing a bunch of buildkit fixes (docker buildx), the rootless graduation to stable and a lot of small feature changes, so there is a chance that this breaks existing setups.
There are also small differences in how stuff is packaged: Debian does docker.io and runc (and also containerd in testing / unstable / on our K8S repo) whereas docker.io does docker-ce and containerd.io, so if a downstream role touches the packages it would also break.

Docker compose
I added an option to install docker-compose as well. As mentioned in the readme, this pulls a broken dependency which breaks part of the functionality of docker. The workaround of installing pass and gnupg2 fixes these though.
(https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=910823)

I assume you mean docker_install_compose? That was there before. I guess the installation of those two packages is harmless for the other docker repo so that seems fine.

docker_users
This PR also adds a task with which docker-users can be added by putting them in the list docker_users.

👍