Remove post macro from api::core::emergency_access::post_emergency_access or add to routes!

[api::core::emergency_access::post_emergency_access]( is only ever used once in put_emergency_access, and the Route is not added by routes! in routes. Three fixes are:
• add the Route via routes! in routes.
• Remove the post macro.
• Remove the function altogether and integrate its body into put_emergency_access.