Add frontend to cargo, activity and port mappings

[andrewsage]

The problem
Due to a mix of inconsistent terms and spellings used on the initial written records and inconsistencies during the transcription process there are multiple ways of describing the same thing - e.g. Good, Goods, Goods, Goods Light.

Mapping files have been created for:

• Cargo
• Activities (cargo that is actually an activity rather than a physical item)
• Registered Ports
• From Ports

However these files have to be edited in the source repo.

Describe the solution you'd like
It would be useful to create a frontend that would allow the mappings to be configured by non-technical users.