Forest & Lotus devnet

[LesnyRumcajs]

Summary of changes

Changes introduced in this pull request:

• use the new fil-actor-states that include the devnet CIDs chore: support devnet cids fil-actor-states#124,
• parameterized block delay and propagation delay so the values are not hard coded,
• Fix race condition in chain exchange #2934 fix is merged into the branch,
• fix: use the KeepAlive libp2p behavior #2935 is merged into the branch,
• genesis pledge - either resolved in this PR if it affects consensus or create a low-priority issue -> Investigate genesis pledge mismatch #2937
• refactor compute_tipset_state_non_async and compute_tipset_state so that they are one again,
• network configuration no longer customisable - there is only one true devnet (defined by Lotus, oh well),
• Create a compose file with the miner + lotus + forest, update instructions,

- [ ] Try sending some FIL to assert that Forest is usable in such a setup. It'd be great to have it in the CI in some form. #3034

Reference issue to close (if applicable)

Closes #2816

Other information and links

Change checklist

• I have performed a self-review of my own code,
• I have made corresponding changes to the documentation,
• I have added tests that prove my fix is effective or that my feature works (if possible),
• I have made sure the CHANGELOG is up-to-date. All user-facing changes should be reflected in this document.

[elmattic]

@LesnyRumcajs if you fix merge conflicts ⚠️, I can review this PR.

[aatifsyed]

Some of the content from the meeting earlier this week belongs here:

• what is a devnet?
• how is it expected to be used?
• design choices:
  • named devnets vs infinitely configurable ones

...etc

[LesnyRumcajs]

#3054

I'd rather this not be in the source code but in the developer handbook, but it's something secondary.