[ATEAM-13094]: Implement Alibaba OSS backend

[kadetutu]

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Fixes [#65] (#65) Add Alibaba OSS Storage Backend
Is your feature request related to a problem? Please describe.

As a user of the Alibaba Cloud, I want to use Alibaba OSS Storage to persist my cache, so that I can reuse the storage system that I already know.

Describe the solution you'd like
Alibaba OSS Storage Backend

Describe alternatives you've considered
using a separate storage backend that already exists in drone-cache

Additional context
none

Proposed Changes

• Implemented Alibaba OSS backend storage for caching
• Updated relevant codes for the addition of alioss backend module
• Updated ReadMe file to reflect new addition

Description

• Added alioss module with functions to implement backend storage interface using aliyun SDK
• Updated Backend package config with settings for alioss configurations
• Updated plugin CLI flags with options for alioss
• Updated ReadMe file to reflect newly added storage backend (Alibaba OSS)

Checklist

• Read the CONTRIBUTING document.
• Read the CODE OF CONDUCT document.
• Add tests to cover changes.
• Ensure your code follows the code style of this project.
• Ensure CI and all other PR checks are green OR
  • Code compiles correctly.
  • Created tests which fail without the change (if possible).
  • All new and existing tests passed.
• Add your changes to Unreleased section of CHANGELOG.
• Improve and update the README (if necessary).
• Ensure documentation is up-to-date.

[spier]

Great work @kadetutu and @bdebyl !

Should we also list the Alibaba OSS Storage Backend in the documentation here:
https://github.com/meltwater/drone-cache#supported-storage-backends

[kadetutu]

Thanks @spier for pointing this out. I will work on updating the documentation.