### What problem does this PR solve?
Restrict file move operations: prevent moving a folder to itself or to
one of its own subfolders.
### Type of change
- [x] Bug Fix (non-breaking change which fixes an issue)
### What problem does this PR solve?
Files /file API to RESTFul style.
### Type of change
- [x] Documentation Update
- [x] Refactoring
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Co-authored-by: writinwaters <cai.keith@gmail.com>
Co-authored-by: Liu An <asiro@qq.com>