Allow to generate and use metainfo 2 python modules.

nomad/cli/dev.py

nomad/cli/parse.py

nomad/datamodel/metainfo/__init__.py

nomad/datamodel/metainfo/common.py

nomad/datamodel/metainfo/general.py

nomad/datamodel/metainfo/public.py

nomad/metainfo/elastic_extension.py

nomad/metainfo/legacy.py

nomad/metainfo/metainfo.py

nomad/metainfo/templates/environment.j2

nomad/metainfo/templates/package.j2

nomad/parsing/metainfo.py

nomad/utils.py

tests/metainfo/test_legacy.py

tests/test_datamodel.py