chore: add additional testcases for fswap

[jaeseung-bae]

Description

• add more tests for fswap

Motivation and context

How has this been tested?

Screenshots (if appropriate):

Checklist:

• [x] I followed the contributing guidelines and code of conduct.
• [x] I have added a relevant changelog to CHANGELOG.md
• [ ] I have added tests to cover my changes.
• [ ] I have updated the documentation accordingly.
• [ ] I have updated API documentation client/docs/swagger-ui/swagger.yaml

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 68.83%. Comparing base (6054848) to head (28b44ed). Report is 1 commits behind head on main.

Additional details and impacted files

[](https://app.codecov.io/gh/Finschia/finschia-sdk/pull/1415?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Finschia) ```diff @@ Coverage Diff @@ ## main #1415 +/- ## ========================================== + Coverage 68.66% 68.83% +0.16% ========================================== Files 767 767 Lines 63512 63512 ========================================== + Hits 43611 43717 +106 + Misses 17234 17135 -99 + Partials 2667 2660 -7 ``` [see 8 files with indirect coverage changes](https://app.codecov.io/gh/Finschia/finschia-sdk/pull/1415/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Finschia)