feat: Add EventsRoot field to message receipt

[iand]

Related Issues

Part of #9473

Uses filecoin-project/filecoin-ffi#332

Proposed Changes

Follows proposed FIP for actor events

Important changes in chain/types:

• Adds a new EventsRoot field to MessageReceipt
• Adds new Event and EventEntry types

Additional Info

Checklist

Before you mark the PR ready for review, please make sure that:

• Commits have a clear commit message.
• PR title is in the form of of <PR type>: <area>: <change being made>
  • example: fix: mempool: Introduce a cache for valid signatures
  • PR type: fix, feat, build, chore, ci, docs, perf, refactor, revert, style, test
  • area, e.g. api, chain, state, market, mempool, multisig, networking, paych, proving, sealing, wallet, deps
• New features have usage guidelines and / or documentation updates in
  • Lotus Documentation
  • Discussion Tutorials
• Tests exist for new functionality or change in behavior
• CI is green

[raulk]

This were a side effect of adding a docs example for the *cid.Cid type. I'm inclined to keep them even though the CID prefixes may be wrong in some cases. If someone complains, we might have to add CID newtypes to attach specific CID examples to them.

[raulk]

Staging into feat/nv18-events.