Module reserve represents fractional balances, so it should be hidden to consumers to not have a misleading total balance that doubles the fractional balances. This modifies GetBalance() and SpendableCoin() to always return zero coins when fetching the reserve address balance for fractional amounts.
Change GetBalance() to return full balances instead of spendable to align behavior with x/bank. Add SpendableCoin() method with support of akava for use in x/evm.
Implement GetBalance for extended balances which passes through to `x/bank` for non-extended denoms. This diverges from `x/evmutil` behavior which will panic on non-"akava" calls.
Add bank / account keeper mocks for testing, with mockery config for [mockery package setup](https://vektra.github.io/mockery/latest/migrating_to_packages/)
