Allow permitDynamic destination state to be calculated with an async function (Task)

[Jon2G]

No description provided.

[mclift]

Thanks for taking the time to contribute, @Jon2G

As there's no issue associated with this PR, I'm curious to know if this addresses a particular problem you've encountered or if it's intended purely to bring parity between the synchronous and the async configuration methods.

Some feedback on the unit tests (thank you for writing them!):

• Some of the new methods don't appear to have test coverage; it would be good to make sure they all have tests.
• Many of the tests include a short delay that doesn't seem necessary; could they return immediately? Something like .PermitDynamicAsync(Trigger.X, async () => await Task.FromResult(State.B)) perhaps?

[Jon2G]

Hi, first of all thank you for making this awesome project!!, state machines should be a standard in programming!
There is no issue, i just needed a way to determine what should be the next state dynamically with a a task/async function.
I made the changes you requested.