Epic: Actor events implementation

[raulk]

This issue tracks the implementation of FIP draft for Actor Events: filecoin-project/FIPs#483.

Basics

• Common types in fvm_shared.
• validate method in dagcbor codec to structurally validate event payloads
  • dag-cbor: add ability to validate input without fully deserializing ipld/libipld#158
  • Moved to Events: lift value type restriction to allow any DAG-CBOR encoded type #1111.
• record_event syscall in SDK and kernel; accumulation of events in CallManager.
• Return events in receipts via Executor.
• Snake through events via filecoin-ffi to client.
• Gas hooks and (parameterized) price formulae for recording events.
• Implement and integrate event store?
  • Moved to Events: implement and integrate an event store #1108.

EVM runtime integration

• Implement LOG opcodes.

Gas params

• Parameterize gas for events.
  • Moved to Events: parameterize gas for events #1109.

PRs

• ref-fvm
  • add support for actor events. #1049
• builtin-actors
  • EVM runtime: implement LOG{0..4} opcodes by emitting actor events (FIP-0049) builtin-actors#839
• filecoin-ffi
  • propagate actor events and Receipt::events_root. filecoin-ffi#332
• fil-actor-utils
  • https://github.com/filecoin-project/filecoin-actor-utils/pull/1

[raulk]

This was landed in Topaz, and all leftovers were moved to their dedicated issues.