Fix reserve minting an extra coin when the recipient module both carries fractional over to integer balance AND remainder is insufficient. Adjusts fractional carry to simply send from reserve, instead of doing an additional mint. Add invariant to ensure reserve matches exactly with fractional balances + remainder, failing on both insufficient and excess funds.
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/)
