### What problem does this PR solve?
- Add comprehensive RBAC support with role and permission management
- Implement CREATE/ALTER/DROP ROLE commands for role lifecycle
management
- Add GRANT/REVOKE commands for fine-grained permission control
- Support user role assignment via ALTER USER SET ROLE command
- Add SHOW ROLE and SHOW USER PERMISSION for permission inspection
- Implement corresponding RESTful API endpoints for role management
- Integrate role commands into existing command execution framework
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
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Signed-off-by: Jin Hai <haijin.chn@gmail.com>
### What problem does this PR solve?
As title.
### Type of change
- [x] Bug Fix (non-breaking change which fixes an issue)
Signed-off-by: Jin Hai <haijin.chn@gmail.com>
