Add MsgSwapWithinBatch Verification and Fix OfferCoinFee Calculation

[dongsam]

Problem Definition

Currently, during the MsgSwapWithinBatch verification phase of MsgServer, if OfferCoinFee is zero, it is calculated and filled according to the current SwapFeeRate.

However, this method does not specify OfferCoinFee exactly in the msg, which can cause confusion that users expect.

so after this update, the proper OfferCoinFee should be in MsgSwapWithinBatch

and there is also a risk of using a small OfferCoin to pay less OfferCoinFee because it is currently being truncated when calculating OfferCoinFee, So It change to Ceil

• v1.2.x: MsgSwapWithinBatch.OfferCoinFee should be OfferCoin * params.SwapFeeRate with Truncate or 0
• v1.3.x: MsgSwapWithinBatch.OfferCoinFee should be OfferCoin * params.SwapFeeRate with Ceil

Proposal

1. When calculating OfferCoinFee, the decimal points are rounded up.

2. Add test code for MsgSwapWithinBatch validation and OfferCoinFee calculation

3. Corrected the missing part of the Spec doc and updated the above.

4. Fix reserveOfferCoinFee residual Issue due to decimal error

For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate contributors tagged
• Contributor assigned/self-assigned