Process instance suspend itself, the process instance can never be activated.

**Describe the bug**
When **I use a execution listener to suspend the current process instance**, all the executions, tasks, jobs will be suspended.
However, after the execution listener completed, **the process seems to create a new execution or task, and the new execution or task has not been suspended.**
By this time, **the process instance can never be activated**, beacuse when I try to activate the process, the new task has not been suspended, so it also can not be activated, and throw the FlowableException "Cannot set suspension state active for xxx : already in state active."
**What's more, I can't even delete the current process instance, because it is suspended.**

**Expected behavior**
However, I use Signal Intermediate Catching Event to implement my requirement.
But I think it is better to do a validation when execute the suspend commend, and if a process instance try to suspend itself, throw an exception to warn the user this error usage.

Inizia riproducendo il caso in cui un’istanza di processo sospende se stessa da un Execution Listener, quindi traccia il comportamento della sospensione e della successiva attivazione o eliminazione. Il lavoro è completo quando il comando di sospensione gestisce questo caso di autosospensione in modo coerente, inclusi l’avviso o l’eccezione previsti, senza lasciare esecuzioni o task non sospesi.

Scritto dal modello di indicizzazione a partire dal testo della issue.