Due to rounding, the LPTokenBalance of the last LP might not match the LP's trustline balance. This was fixed for `AMMWithdraw` in `fixAMMv1_1` by adjusting the LPTokenBalance to be the same as the trustline balance. Since `AMMClawback` is also performing a withdrawal, we need to adjust LPTokenBalance as well in `AMMClawback.`
This change includes:
1. Refactored `verifyAndAdjustLPTokenBalance` function in `AMMUtils`, which both`AMMWithdraw` and `AMMClawback` call to adjust LPTokenBalance.
2. Added the unit test `testLastHolderLPTokenBalance` to test the scenario.
3. Modify the existing unit tests for `fixAMMClawbackRounding`.
* Add AMM bid/create/deposit/swap/withdraw/vote invariants:
- Deposit, Withdrawal invariants: `sqrt(asset1Balance * asset2Balance) >= LPTokens`.
- Bid: `sqrt(asset1Balance * asset2Balance) > LPTokens` and the pool balances don't change.
- Create: `sqrt(asset1Balance * assetBalance2) == LPTokens`.
- Swap: `asset1BalanceAfter * asset2BalanceAfter >= asset1BalanceBefore * asset2BalanceBefore`
and `LPTokens` don't change.
- Vote: `LPTokens` and pool balances don't change.
- All AMM and swap transactions: amounts and tokens are greater than zero, except on withdrawal if all tokens
are withdrawn.
* Add AMM deposit and withdraw rounding to ensure AMM invariant:
- On deposit, tokens out are rounded downward and deposit amount is rounded upward.
- On withdrawal, tokens in are rounded upward and withdrawal amount is rounded downward.
* Add Order Book Offer invariant to verify consumed amounts. Consumed amounts are less than the offer.
* Fix Bid validation. `AuthAccount` can't have duplicate accounts or the submitter account.
