This will reject blocks in pubsub validation if they're either:
1. Too far into the future (5 blocks beyond the expected head).
2. Too far into the past (before finality with respect to our current
head).
Specifically:
1. We were previously rejecting future blocks in the sync logic, but not
in pubsub itself.
2. We never used to check if a block was too _old_.
Motivation: Blocks that are too new/too old can cause us to perform
quite a bit of unnecessary work.
We need to use the height at which the messages will be executed, not
the height of the previous tipset. This brings the gas checking for
validation with the gas we actually _charge_ during message execution.
This only matters for the Calico upgrade (the only upgrade where we
changed the gas prices).
This change could potentially cause a block at that height to be
rejected if it includes a message with insufficient gas for inclusion.
However, that _should_ have shown up as a miner penalty when we executed
the blocks in the following tipset. Given that there were no miner
penalties at 265199-265201, this change should be "safe".
- FSM handles the actual cc upgrade process including error states
- PoSting (winning and window) works over upgraded and upgrading sectors
- Integration test and changes to itest framework to reduce flakes
- Update CLI to handle new upgrade
- Update dependencies
