### What problem does this PR solve?
Update displayed_name to display_name
### Type of change
- [x] Refactoring
Co-authored-by: liuhua <10215101452@stu.ecun.edu.cn>
### What problem does this PR solve?
Fix bugs in agent api and update api document
### Type of change
- [x] Bug Fix (non-breaking change which fixes an issue)
- [x] New Feature (non-breaking change which adds functionality)
---------
Co-authored-by: liuhua <10215101452@stu.ecun.edu.cn>
### What problem does this PR solve?
Add sdk for list agents and sessions
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
Co-authored-by: liuhua <10215101452@stu.ecun.edu.cn>
### What problem does this PR solve?
Fix test cases
### Type of change
- [x] Other (please describe): Fix error cases
---------
Signed-off-by: jinhai <haijin.chn@gmail.com>
### What problem does this PR solve?
Add tests for frontend API
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
---------
Co-authored-by: liuhua <10215101452@stu.ecun.edu.cn>
