Potentially non-unique AuthenticatedIdentity under JWT Auth

[viathefalcon]

Describe the bug
Callers who elect to authenticate via JWT are identified by the JWT's issuerKey which may not be unique to any given caller, c.f.

did-ccf/src/models/AuthenticatedIdentity.ts

Line 58 in 560274c

return (<JwtAuthnIdentity>identity).jwt.keyIssuer;

Expected behavior
Authenticated identities to be unique per entity regardless of the auth mechanism

Additional context
Thanks to Amaury Chamayou (@achamayou) for pointing this out.