state_machine chore(state) expose __none_

Motivation

I'm listening to a state onEnter event to perform some database changes when a transition happens.

I noticed that this event was triggered also just after the stm.start(initialState); line.

To cope with this event and ignore this first initial transition I checked the source code and found that this event has a stub __none__ state.

So in my code I ended up with this:

state.onEnter((change) {
  if (change.from.name != '__none__') {
    // do something
  }
});

I think this is not the best approach as I'm relying on some internal representation. That's why I'm exposing this State.isNone getter.

Exposed State.isNone and StateChange.isInitial to distinguish initial state change events.

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Please review:

[x] Tests were updated and provide good coverage of the changeset and other affected code
[x] Manual testing was performed if needed
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Apr 03 '20 21:04 lidio601

No security relevant content was detected by automated scans.

Review PR for security impact; comment "security review required" if needed or unsure
Verify aviary.yaml coverage of security relevant code

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Apr 03 '20 21:04 aviary-wf

hi there, how's going with this one?

Apr 23 '20 05:04 lidio601

@lidio601 if you could run dartfmt and commit the changes, we should be able to get this merged. Thanks!

Jul 07 '20 19:07 evanweible-wf