Separate the dispatch internal state from the immutable `Dispatch` object

[llucax]

Since the Dispatch's deleted bool and running_state_change_synced are only attached as mutable properties for internal state tracking, it might make more sense to separate the state from the immutable dispatch, and have a DispatchState mutable class and a separate dict to map dispatch ID to its state, for example.

You can pass the state object to the Dispatch constructor and store it as a private property and expose read-only properties to access the state, if it needs to be accessed externally, and store the dict and mutate it from this actor only.

Originally posted by @llucax in #54 (comment)

[Marenz]

in #82 running_state_change_synced was removed