chore: remove dependencies on api

[geoff-vball]

Related Issues

Closes #9825

Proposed Changes

Moves a bunch of stuff around so that packages that shouldn't depend on api don't have to anymore.

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

[arajasek]

@geoff-vball Thanks for this! I need to think a bit more about whether we want to move things like HeadChange etc. into the core consensus types. It's a tradeoff between severing odd dependencies on API types vs. bloating the core consensus types.

How doable would it be to land just the last commit? That's the one I'm keenest on, because the only change urgently needed (blocking v18) IMO is having the core chain validation (state computation) path run through API types.

[geoff-vball]

Might get to these changes later. For now, just making minimal changes in #9872