Add global node index

[marcospassos]

Summary

Rendering JSX requires a key, which the developer must handle. To make it easier, this PR adds a new index property with a globally unique index for a given parsing.

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• I have checked my code and corrected any misspellings

[github-actions]

👋 @marcospassos
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