* runservice: use generic task annotations instead of approval annotations
* runservice: add method to set task annotations
* gateway: when an user call the run task approval action, it will set in the
task annotations the approval users ids. The task won't be approved.
* scheduler: when the number of approvers meets the required minimum number
(currently 1) call the runservice to approve the task
In this way we could easily implement some approval features like requiring a
minimum number of approvers (saved in the task annotations) before marking the
run as approved in the runservice.
All the validation must be done inside the configstore since it's the source of
truth.
The gateway could also do some validation to avoid bad requests to the
configstore when needed or when the logic resides outside the configstore (like
project setup or user registration)
