post https://{environment}.plugsurfing.com/emp/v1/sessions/start
Starts a remote charging session with the given charging key on the given connector.
If a user has CREDIT_CARD payment method, and 3DS challenge mode is set to CHALLENGE, then threeDSClientSecret might be present instead of sessionId, which your frontend needs to prompt the user to sign. After the user successfully signs the challenge, do a second start request!