feat: add aliyun oss storage

[henrybit]

Description

Use Aliyun oss to store files, need oss2>=2.15.0 library.

Type of Change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

1. use my Aliyun ram account's token(AK/SK), create a private read/write bucket, grant full control permission to my ram account;
2. start API & Web server locally, use Milvus/Redis/Postgresql in My Environment;
3. create a knowledge repository, and upload some PDFs.

results: Upload success/Content vector successfully obtained/Chat success in RAG.

[takatost]

There is a lint issue that did not pass, please fix it.

[JohnJyong]

@henrybit

[henrybit]

There is a lint issue that did not pass, please fix it.

fix this lint issue.

[henrybit]

@henrybit

finished.

[JohnJyong]

thanks for your contribution~