Xstate: Allow autoForwarding of events to spawned actors

[gabewillen]

Bug or feature request?

Feature

Description:

Since spawn essentially wraps an invoke element, allow passing in the attribute autoForward so that events can be sent to spawned actors.

(Feature) Potential implementation:

Should be fairly straight forward and If I get time i'll submit a pull request for this feature. In the mean time this will be a reminder.
Required! If you would like to see a feature or enhancement make its way to xstate, please describe:

• What the API would look like

spawn(SomeMachine, {autoForward: true});

• Is this is a breaking change
  No
• If this is part of the existing SCXML specification
  It is part of the invoke specification and currently implemented with the invoke property of a state.
  You can use CodePen or Code Sandbox to create a reproduction/POC.

[Andarist]

Just letting you know - I have started working on this one.