Pulp

Use Docker rather than k3s-bundled containerd

So that built & cached images can be used later during CI.

This means that the pulp-operator CI now actually tests the current version of the image it builds, rather than the version from quay.

re: #5062 Create pulpcore and pulp_file container images automatically via CI https://pulp.plan.io/issues/5062

containers: Build both stable and dev images

and make images far more configurable.

Implementation includes:

Build stable and master (latest) versions (tags) of both images.

Use an undefined plugins list for no plugins ather than the dummy pulpcore-plugin.

Use variables for the pulpcore & pulpcore-plugin pip installs

Use vars/vars.yml as an override for vars (including the images data structure.)

Start work on installing into the container, and limit the CI builds to only pulpcore & pulpcore-plugin stable.

fixes: #5116 Handle properly whether to build container images with pulpcore stable or dev (Actually does more than that.) https://pulp.plan.io/issues/5116

Includes some work on: re: #5062 Create pulpcore and pulp_file container images automatically via CI https://pulp.plan.io/issues/5062

containers: Support pip install from Travis host dirs

Implementation includes: Copying the host dirs into the Docker build environment

Setting the Docker build "context" to the parent dir of the checked out pulpcore (So that it and all the other cloned repos can be accessed during docker build.)

Users must specify host dirs as relative to the parent dir of pulpcore, and begin them with "./". This triggers copying logic.

Templating the Dockerfile with jinja2, with some Ansible-bundled filters. (We've outgrown what env vars in the Dockerfile can do.)

Remove unused Dockerfile variable VERSION

.travis/post_script.sh: Build pulpcore & pulpcore-plugin from Travis host dirs

[noissue]

Partially implements: re: #5062 https://pulp.plan.io/issues/5062 Create pulpcore and pulp_file container images automatically via CI