basesections.py classes and normalizers improvements

• ExperimentStep normalizer (see comment below)
• Add FileEditQuantity to Measurement ELN (see comment below)
• set PubChemPureSubstance as default
• check that workflow2.name is filled in every case
• support for adding one component at a time is missing
• the basic ElementalComposition should not be editable (or completely moved in Results)
• figure out if "tags" quantity should be a deprecated or not
• Rename smile to smiles in PureSubstanceSection: SMILES is the correct abbreviation.
• check once again the datetime timezone
• archive.results.eln what do we do with this section?
• archive.results.eln.instruments is present in some normalizer, think about what to do with this
• ReadableIdentifiers None check: !1985 (comment 283035) https://en.wikipedia.org/wiki/Simplified_Molecular_Input_Line_Entry_System
• harmonize and populate the topology from the new system classes
• python if self.owner is None or self.institute is None: @lukaspie commented: Are these None by default? If not, get_attr might be safer.
• include Instrument in the workflow graph. @lukaspie
• separate out (somehow) the normalizer for chemical descriptor in pure substance @ndaelman @g-bernadettemohr
• search_results = search(...) is used several times. Try to make a general method for that
• archive.results.eln.lab_ids why do we need this "backfilling" of the lab_id from results?
• figure out the tags: if/where to include a normalizer for that