[FEATURE REQUEST] support for file versioning

## It would be super helpful to have file-versioning to enable rollback on overwritten files.

I am aware that the server can be configured to rename files for versioning, instead of overwriting, but it would be nice to have a management layer to provide UI-accessible version-control within a single file node.

Since the file-transfer library already manages uploads as chunks, the ideal solution would be a block/chunk level version controller such as [bup](https://bup.github.io/) or [restic](https://restic.net/).

### Unfortunately, Bup is not maintained, so you would need to fork it / rip it into your project, and Restic does not currently have a python interface, and does not provide native diff tools.

If you are inspired by the idea of a file-versioning feature, I would be open to collaborating or even prototyping an implementation, but of course that's a pretty huge feature for someone who is new to your code base.

#### P.S.
Thanks for your hard work, this project is really phenomenal, and you should be very proud!

该 issue 提到，file-transfer library 将上传内容作为 chunks 进行管理。查看上传处理代码，以了解 chunk 系统。研究 bup 或 restic，了解块级版本控制的概念。原型需要将版本控制集成到现有的文件节点管理中，可能是在后端存储层中实现。

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