clara_manager: refactor expected request string

- Replace delimiter with ':', since the data may contain '/' (for
  example, orchestrator arguments)
- Move 'action' to the second position. The action should have more
  priority when parsing the request, since it may not need the next
  fields.
clara_manager: force kill of Clara processes

Try to stop the Clara process normally first and wait a few seconds.
If the process did not terminate after the timeout, kill it by force and
report an error. Ideally, Clara processes should have a clean exit.
Dispatch request to stop all Clara instances