API lifecycle management

[DawMatt]

• Add multiple major versions of the same API into Backstage at the same time, to represent multiple versions running in production in parallel
• Demonstrate how the multiple API versions would all be searchable and accessible, but the most recent version would be prominent and the only one offered to a new user looking for this type of API.
• Show how we would represent APIs progressing through the main lifecycle: development, test, production. Including how these lifecycle states can vary across each API version.
• Show how we manage API retirement. Including marking APIs for deprecation and then retiring them.