feat: Add state-modifying retry policies

[NikitaZelenskis]

Add state-modifying retry policies

Description

This PR adds support for state-modifying retry policies by allowing a dictionary mapping of exceptions to state-modifying functions in the RetryPolicy class. This enhancement enables users to modify the workflow state before retry attempts based on specific exceptions.

I think this feature can be very usefull as I am not the only one who needs it. See this discussion

Changes

• Extended RetryPolicy's retry_on parameter to accept dict[Type[Exception], Callable[[Any, Exception], None]]
• Updated type hints and documentation
• Added tutorial section explaining the new functionality

Tests

I have not added a test for this feature as I did not find a a fitting file name for this case and did not want to make my own test file.
If needed I can add a test for this new feature, I would appreciate guidance on the preferred location for adding tests.

All existing tests pass.

[NikitaZelenskis]

Also as I understand the State/task input can be any type? If that is not the case I would also appreciate some guidance on that