[wallet] Dynamically fetch ConsensusApp bytecode from the chain on wallet start

[snario]

As of #519, the bytecode for ConsensusApp is loaded as a constant in constants.ts. It is preferable to auto-fetch this from the blockchain when the wallet first starts.

[andrewgordstewart]

It's probably safe to punt this, since I think we're just going to axe the ConsensusApp.

[snario]

@andrewgordstewart going to use 0x0 for appDefinition?

[andrewgordstewart]

I think so, in which case the wallet doesn't need to call validTransition (because there are no valid transitions).

There may still be value in calling a function

thesebytesAreIndeedAState(bytes calldata maybeAState) public pure {
  abi.decode(state, State); 
}

in lieu of calling validTransition(s1, s2). But we might be content to call a javascript implementation of abi.decode from ethers, for instance.

[lalexgap]

Refers to the old wallet