Add EIP-5902: Smart Contract Event Hooks

[orbmis]

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[eth-bot]

All tests passed; auto-merging...

(pass) eip-5902.md

classification
updateEIP

• passed!

[orbmis]

This is a very interesting EIP. Thank you for your authoring. Will take a look

Thanks @xinbenlv . I fear it's not that obvious how subtly different this is from existing alternatives so I'm happy to answer any questions.