[tripleo][ansible] ensure python dependencies on hosts for modules/plugins

Since most of tripleo-ansible modules do 'import foobar', we should ensure that we have the corresponding python packages installed on target hosts. Some of them, like python3-dmidecode may be in base Centos8 images. But some may not, especially for custom deployed-servers provided by users for deployments.

Those packages must be tracked and ensured to be installed by tripleo (preferred), or validated deploy-time (nah...), or at least documented as the modules get created or changed by devs.

That also applies to adding action plugins' deps for python-tripleoclient or tripleo-ansible perhaps.

Shall we write a spec for that or just address that as a bug [0]?

[0] https://bugs.launchpad.net/tripleo/+bug/1894957