more informative return value of dex predeploy

[shunjizhan]

currently for our dex predeploy, all actions (swap, addliquidity, removeliquidity) returns bool. However, usually these actions return more informative data such as amountOut, shares, which will be helpful for predicting action result.

For example, if we want to get the estimated share amount when adding liquidity, now we have to do some manual calculation, which isn't that convenient

[zjb0807]

These changes will affect the work of existing contracts. We can add some _v2 methods to implement it.