Improve bridgeState naming for clarity

[troggy]

bridgeState object is not representing a bridge state anymore. It rather represents the whole node's transient state + app/consensus state (what we call currentState).

Suggested to rename it like this:

1. Rename bridgeState to nodeState or just state.
2. Rename bridgeState.currentState to nodeState.consensusState. This object is used to generate app hashes for tendermint — nodes agree on the state of things upon it, hence the name consensusState.

nodeState.js:

nodeState = {
  ...
  consensusState: { 
    ... 
  }