As SGP.22 states, the handleNotification endpoint uses HTTP status 204,
not 200 (due to its empty body).
Change-Id: I890bdbd3e1c4578d2d5f0367958fdce26e338cac
Let's use the infrastructure of pySim.esim.http_json_api to define
the ES9+ API Functions. This can in turn be used by clients or even
osmo-smdpp can be ported over to using this infratructure rather than
open-coding a lot of the encoding/decoding of API request/response
parameters.
Change-Id: I194ef1d186391f36245c099cc70a4813185ecf9c