Metador CLI infrastructure

[apirogov]

Eventually, a CLI tool should be provided, with following features:

• list existing installed plugin groups and plugins (feature of the plugingroup plugingroup)
• either each plugin group can register its own sub-cli app, or make CLI sub-apps another plugingroup

The schema CLI should allow to validate JSON or YAML against an installed schema plugin (and let it output what it parsed), which could be very helpful for schema development

The packer CLI should provide an interface to pack or update containers based on some input directory

[broeder-j]

Also I would add a command:

metador generate_display(containerfile.h5)

or

metador show/display(containerfile.h5)

Which will open the default metador dashboard container vis for this container in a browser.
useful for looking at stuff outside of the Webpage, also useful for debugging Dashboards during development.
The command should be there in python of course and only exposed through the CLI