NOMAD Metainfo refactor

There should be some coordinated effort to clean up the NOMAD Metainfo

• parser specific metainfo should really be parser specific ... there are some that miss the x_... prefix
• only have one common code file/package for computational
• have an extra package for workflows
• refactor names, make use of aliases
• get rid of sampling method and frame sequence
• remove repeats were applicable
• add derived for normalised quantities
• analyse which quantities are not used at all via ES
• how to deal with "external" references (to other archive objects, to binary files, and files in general)
• a set of public metadata for "elastic" properties (#407 (closed))
• a set of public md properties
• further classification of non crystalline systems (e.g. amorphous solids/glass)

Related to: #308 (closed), #289, #358, #407 (closed)