HTTPS Callable Functions

Equivalent of -

- name: myHttpsCallableFunction
type: httpsCallable
# Since 'httpsCallable' function is meant to be called
# from inside your app by your users, it expects a
# field 'asUser'
# With this field you specify as what user should this
# function be triggered
# A user with this ID must be present in the emulated Firebase Auth users
id: user-id
# The 'payload' field is the same as in the 'https' function
payload: '{}'