Extend provable events in the block metadata transaction

[peternose]

Last results hash is needed if a stateless light node wants to verify events from the last block.

Provable events need to be extended if a stateless light node wants to verify events from the last block.

[kostko]

Should we instead extend what events are included in the existing provable events root?

[peternose]

In that case, we need to make events from all services provable, i.e. events from beacon, roothash, registry, staking, ..., vault. Furthermore, a stateless node cannot verify response from GetBlockResults for the last height (unless we change this by filtering only provable events). And the change is still breaking.

[kostko]

I believe events are missing from LastResultsHash, see the canonicalization function which excludes events. This is why we needed to add the provable events root in the first place.