pkg references moved from pkg

pkg/content/client.go

pkg/content/content.go

pkg/extension/action.go

pkg/extension/schema_test.go

references/field.go

references/field_test.go

references/middleware/access_logging_middleware.go

references/middleware/client_encode_middleware.go

references/middleware/error_logging_middleware.go

references/middleware/middleware.go

references/middleware/recovering_middleware.go

references/middleware/telemetry_middleware.go

references/mocks/Middleware.go

references/mocks/References.go

references/reference.go

references/reference_test.go

references/service.go

references/transport/client.go

references/transport/endpoints.microgen.go

references/transport/exchanges.microgen.go