Building on D9393, this diff now adds utxo information to the cached wallet state. On app start, if the wallet has a cached state and utxo set is unchanged, the app pulls this in rather than querying server for full history.
Because BigNumber type information is lost in the caching to IndexedDb, a helper function is added to convert cached token utxo info back to what is calculated in the app. This function includes a unit test.