x/upgrade: enforce valid genesis state

[alexanderbez]

Summary

It's technically possible to have an on-chain upgrade with invalid genesis state that would result in a functional network.

Consider the upcoming Hub's Theta upgrade. This upgrade includes an SDK version bump to 0.45 which has x/bank metadata changes. Assuming the developers are unaware of these changes and what would constitute a valid state, then it's completely possible to miss setting the correct and expected metadata for assets.

However, the upgrade and network will still "work" in this particular case.

Proposal

My proposal is simple, require that the SetUpgradeHandler method in x/upgrade calls ValidateGenesis after executing the upgrade closure function.

1. Update SetUpgradeHandler to accept the ModuleManager as an argument
2. Update the ModuleManager interface to have a method that validates genesis state. There already is one but that only works on raw data. We need a method to call on already existing data in state. Perhaps ValidateState or ValidateGenesisState.
3. Call the method in (2) after the closure function is called in SetUpgradeHandler.

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