Use public OBS and PyPI

[zeromind]

We're publishing packages for dimclient and ndcli on the public OBS and PyPI now;
we should update our documentation and VM/Dockerfiles to use them where appropriate.

On OBS we currently have packages for:

• Debian
• Ubuntu
• openSUSE
• Fedora
• Arch
• EL

The GitHub actions currently create packages only for:

• Debian
• Fedora
• EL

It is much easier to support more, or newer versions of Linux distributions via the public OBS instance instead of GitHub actions:

• the current workflows as implemented do not allow resolving packagaging issues without re-tagging the version
• current workflows are broken since switch to pyproject.toml #283

The build process for dim and dim-web require Internet access to download dependencies; they are easier to build via GitHub still, and will stay there for the foreseeable future.

GitHub actions that can be removed, either completely, or leaving the archive only containing the components' subdir:

• release_dimclient
• release_ndcli

Updating the documentation was already done in #286

OBS project:

• dimclient & ndcli: https://build.opensuse.org/project/show/home:zeromind:dim

PyPI:

• dimclient: https://pypi.org/project/dimclient/
• ndcli: https://pypi.org/project/dimclient-cli/