Network Version 21 upgrade (calibnet)

[LesnyRumcajs]

Issue summary

With the NV21 coming in 6 weeks, it's time we prepare for it and attempt to have a perfect state migration when it lands on calibnet.

The NV21 board for Filecoin can be found here and a discussion there.

In essence, we should start working on the skeleton to deal with details after the code freeze (somewhere end of September). This is the approach that Lotus took.

A non-exhaustive list of tasks to be done, on a separate migration branch:

• Prepare NV21 state migration skeleton. You can use the guide from here
• Add tests to check that the migration will be executed correctly,
• Modify the devnet configuration to have an NV21 upgrade here
• Check if we can already implement some of the finished FIPs
• bultin-actors v12 in fil-actor-states #3527
• We might want to start integrating Forest and fil-actor states with the new ref-fvm.

Other information and links

[hanabi1224]

As per ref-fvm changelog, this is blocked by the release of fvm4

Other Changes:
Add support for nv21 behind the nv21-dev feature flag
Note: We do NOT expect to support nv21 on FVM3, this only facilitates the development of nv21 before FVM4 is ready
We use the Hygge pricelist as-is for nv21 if the nv21-dev feature flag is enabled

[LesnyRumcajs]

@hanabi1224 so we need yet another set of shims for FVM4?

[hanabi1224]

@hanabi1224 so we need yet another set of shims for FVM4?

@LesnyRumcajs I guess yes.