Make UpdateConsensus to choose the proposer

[junha1]

Foundry host eventually has to use the 0th validator given by UpdateConsensus, as the proposer. This will remove old CodeChain proposer selection logic https://github.com/CodeChain-io/foundry/pull/602#pullrequestreview-556853470. And also, to express complicated staking rule considering tendermint process, we have to pass the current view (round) to the module, via block_opened().