move hbm to a managed plugin instead of a legacy one

[xinity]

right now HBM is installed as a legacy plugin: https://docs.docker.com/engine/extend/legacy_plugins/#types-of-plugins

but the supported method to use the plugin is the managed one: https://docs.docker.com/v17.09/engine/extend/

it doesn't seem to be that hard, and it could as well help HBM being widely used and the legacy plugin system isn't anymore advised :)