Automatically validate a DistributionRoot when consumed as an event

[seanmcgary]

Currently, we capture that a DistributionRoot was emitted from the RewardsCoordinator, but we dont validate that it is actually correct using the internal state of the sidecar that consumes it.

To ensure that DistributionRoots are correct, the sidecar should generate a root using the same parameters and compare its result to what was posted on chain.