CU-8699jpw1u Save and load CDB and Vocab as zip

[mart-r]

This applies only when saving and/or loading CDB or Vocab explicitly / on its own, not as part of a model pack.

Allowing this makes it a lot easier for trainer because one file can be uploaded instead of a folder.

This PR

• Adds a utility module with methods to allow to serialise and deserialise objects into zip file
  • As well as a method to figure out whether a zip file should be used
• The procedure is automatic
• If the file path ends with .zip a zip file approach is used
• I.e both for loading and saving
• Though it can be enabled or disabled by the user
• Used the above for Vocab and CDB (both load and save methods)
• Added a few test as well