Merge branch 'metainfo-small-fixes' into 'develop'

gui/tests/artifacts.js

nomad/datamodel/metainfo/plot.py

nomad/datamodel/util.py

nomad/metainfo/data_type.py

nomad/metainfo/metainfo.py

nomad/metainfo/util.py

nomad/parsing/chemotion/chemotion.py

nomad/parsing/tabular.py

tests/metainfo/test_attributes.py

tests/metainfo/test_hash_id.py

tests/metainfo/test_metainfo.py