Fix test testPermitBatchAndCall to check addLiquidity output

[joaobrunoah]

The forge test testPermitBatchAndCall doesn't check if addLiquidity was successful, so a combination of operations in which addLiquidity and removeLiquidity returns 0 would pass the test.

To make it more robust, we can check the addLiquidity event and make sure it returned the expected amount of BPTs and spent the expected amount of amountsIn.