Create symlink via azure.storage.file FileService

### Which service(blob, file, queue) does this issue concern?
Note: for package version >= 12.0.0 please post the issue here instead: https://github.com/Azure/azure-sdk-for-python/issues
for table service, please post the issue here instead: https://github.com/Azure/azure-cosmosdb-python.
azure.storage.file

### Which version of the SDK was used? Please provide the output of `pip freeze`.
azure-storage-file==2.1.0

### What problem was encountered?
I'm trying to figure out how to create a symlink via the azure-storage-file FileService interface. Ideally, the symlink target doesn't need to exist, but I can work around that if need be. To be clear, I want the symlink uploaded, not the content of the symlink'ed file.

I should also clarify I am talking about a soft symlink here.

### Have you found a mitigation/solution?
No, I haven't been able to find a good example of how to accomplish this.

从 azure.storage.file 的 FileService 接口和 azure-storage-file 2.1.0 API 文档开始，重点关注文件上传如何表示符号链接。确定软链接对象是否独立于其目标受到支持，以及哪种 API 行为可以定义完成；该 issue 未指定源文件或测试。

由索引模型根据 Issue 内容生成。