RenameContextOutcome

Result of a context rename. renamed is false when the canonical name already equalled
the stored one (idempotent no-op).

Carries the composed context_ref as well as the owner_ref + slug halves it is built
from: the caller has just had their address changed out from under them, so making them
reconstruct the new one from parts is the wrong place to save a field.

{
    "context_id": "f31d7249-b7b1-4729-b3a4-ec0ba07b4686",
    "context_ref": "string",
    "name": "string",
    "owner_ref": "string",
    "renamed": true,
    "slug": "string"
}