System type processing

Currently SystemNormalizer in branch v0.7.2 supports the following system types:

• 'atom'
• 'molecule / cluster'
• '1D'
• '2D / surface'
• 'bulk'

The MatID package, however, supports to make a separation between 2D and surface systems. I would like to add this functionality to the SystemNormalizer. This separation will become increasingly more important in the future if we add comprehensive support for surface systems in the Encyclopedia. This was already planned in NOMAD-coe, but was not finished.

I already have the implementation in the encyclopedia-branch and the current tests suite passes. I'm not however sure if I would need to change other parts of the code. E.g. the front-end where one can filter by system type?

If you agree with adding this functionality to the next release, could you @mscheidg point if any other changes are necessary. I could also try testing the gui on a local docker-installation. If everything works, I can make a new branch wit the changes that can be merged to 0.7.2.