ag-chain-cosmos unsafe-reset-all needs to reset kernel state too

[michaelfig]

When a validator runs ag-chain-cosmos unsafe-reset-all, the kernel state file should also be reset.

To accomplish that, the kernel state should be kept with all other validator state in $HOME/.ag-chain-cosmos/data/ag-cosmos-chain-state.json. If we ever move that validator directory elsewhere, the kernel state should also move, too.

[michaelfig]

@mabalaru, @awrelll, @warner this proposal would mitigate misbehaviour for people who are accustomed to using Tendermint but not aware that the Agoric state is a different beast. By putting it in the same data directory, it will be backed up, deleted, viewed, etc. at the same time as other validator runtime data.