- Event keys are now t1, t2, t3, t4 for topics; and d for data.
- ref-fvm no longer stores events in the blockstore for us. It just
returns events to the client, who is now responsible for handling
them as it wishes / according to its configuration.
- Add a flag to VMOpts to have the events AMT be written in the blockstore.
- Add a flag to the ChainStore to advertise to the rest of the system
if the ChainStore is storing events.
- Enable that flag if the EthRPC is enabled (can also add an explicit
configuration flag if wanted).
