feat: add multiple workspaces support
- Add getWorkspacePath function to centralize workspace directory path retrieval
- Use the new workspace directory retrieval logic in Cline, Mentions, ClineProvider, and WorkspaceTracker
- Update WorkspaceFile on tab switch and prevent redundant updates by checking prevWorkSpacePath
- Fix the bug that loads the contents of the previous tab when quickly switching tabs
- Optimize getWorkspacePath return value for better reliability
Co-authored-by: xiong <yueminxiong.xym@alibaba-inc.com>