[v5] Improve target resolution

[davidkpiano]

This PR improves target resolution:

• Targeting sibling nodes from the root is no longer valid, since the root node has no siblings

createMachine({
  id: 'direction',
  initial: 'left',
  states: {
    left: {},
    right: {}
  },
  on: {
-   LEFT_CLICK: 'left',
+   LEFT_CLICK: '.left'
  }
});

• Delimiters in state node IDs resolve to the state node from the path relative to the resolved state node ID

createMachine({
  // ...
  on: {
    SOME_EVENT: '#foo.bar' // resolves to whatever.bar
  },
  states: {
    whatever: {
      id: 'foo',
      states: {
        bar: {} // resolves to this state node
      }
    }
  }
});

Closes #500

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: c26249236064e46cabd110297f7c3da8e47e7d9b

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
xstate	Major

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[Andarist]

Gonna test this asap - I've tried to do so a few days ago but the test output is spammed with some unrelated stuff and this made playing with it a little bit harder. Gonna take a second look on Monday or so and also I will try to clean up that test output.

[codesandbox-ci[bot]]

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