Add support for callables as worker callbacks (Drupal 10.2+)
The existing usage of function name strings as worker callbacks are already callables. call_user_func() supports many other types which the Job Scheduler module might as well support.
Inject a CallableResolver from Drupal Core 10.2 and use this to convert all types of callable definitions for worker callbacks to callables.
If the worker callback is invalid then include this exception message in the exception message from Job Scheduler.
Closes #3426366