ListEvents: retrieve events from a list of blocks

[kroggen]

New Feature

Add a field in the FilterInfo structure and update the ListEvents GRPC function so that we could retrieve events from a list of blocks (instead of using a range)

This is useful when we now the blocks in which events were generated

This feature would be required to implement indexing of contract events IF it is chosen to not store all events on the database but just the blocks numbers

It is not needed if storing all the events on an external database