[client] Fix a mistake in the scope of the state in the store.

This MR fixes a small mistake in the scope of the state in the store (there is no bug, the code works fine) : in the substores, the getters are expected to be ignorent to the main store structure. With this fix, Bank.computeAccessTotal is passed the substore state.banks instead of the full state (the calls to the getters in Bank.computeAccessTotal are fixed subsequently.