Serai Coordinate Substrate Scanner

This is the scanner of the Serai blockchain for the purposes of Serai's coordinator.

Two event streams are defined:

• Canonical events, which must be handled by every validator, regardless of the sets they're present in. These are represented by serai_processor_messages::substrate::CoordinatorMessage.
• Ephemeral events, which only need to be handled by the validators present within the sets they relate to. These are represented by two channels, NewSet and SignSlashReport.

The canonical event stream is available without provision of a validator's public key. The ephemeral event stream requires provision of a validator's public key. Both are ordered within themselves, yet there are no ordering guarantees across the two.