Tracking issue: refactor RROS kernel code

## Tracking issue
- [ ] The real-time API identification. (https://github.com/BUPT-OS/RROS/issues/52)
- [ ] Code Detail Design (https://github.com/BUPT-OS/RROS/issues/53)

## Additional Information
- [ ] After refactoring, optimize the real-time performance of RROS based on performance measurement results(https://github.com/BUPT-OS/RROS/issues/49)