Improve schema version handling

[anvabr]

Problem description

Currently there are 3 types of schemas in Guardian which are handled subtly differently:

• published schemas with version
• new version of these published schemas, whether draft or published
• imported schemas which are all introduced into the importing instances of Guardian as draft independent schemas

The UI has not indication wrt which is which, which confuses the user:

Requirements

• Improve the UX such that it is immediately apparent that some schemas (published or not) are new versions of other schemas. This can be done via drop down list of schema versions, with the most recent (draft or published) displayed at the top
• Enforce linear progression of schema versions such that only the most recent published schema can be the source/basis of new versions
• Always display the version of the schema documents
  • for draft new versions of the existing schemas display in italic the suggested version, which is also pre-populated in the schema dialogue but can be overwritten by the user
  • for imported versions of the schema display the version as imported, no italic or any other formatting

Definition of done

• Requirements above are implemented
• Documentation is updated accordingly

Acceptance criteria

• The versions/types of schemas are differentiated visually
• The handling of imported schema can stay as is, i.e. the schemas which have been imported and originally were different versions of the same schema are imported as separate unrelated schemas