Implement exception backoff via configuration

### Scenario

* Library version: 8.5.0
* Description of your use case: (detailed description or executable reproducer, e.g. GitHub repo)

### Current Behaviour
One can throw a `FailJobException` to retry a task with a backoff. However, one has to explicitly throw this exception to get the desired behaviour.

### Wanted Behaviour
One should be able to configure `Throwable`s with a backoff duration. Whenever such a `Throwable` is thrown, _Process Engine Worker_ should automatically use the configured backoff and *not decrement* the affected task's retries.

### Possible Workarounds
In Spring one can throw `FailJobException`s in aspects around `ProcessEngineWorker` invocations.

Start by tracing ProcessEngineWorker invocations and the existing FailJobException backoff path, then inspect how Spring configuration is exposed. Define how configured Throwables map to backoff durations and preserve the affected task's retries; done means the behavior is covered for configured and unconfigured exceptions.

Written by the indexing model from the issue text.