feat(drivers): add Rakuten Drive support

[rufusu]

feat(rakuten_drive): add Rakuten Drive storage driver

Description / 描述

• Added a new RakutenDrive driver with list, link, mkdir, move, rename, copy, delete, upload (S3 multipart), and storage quota support.
• Implemented token refresh + JWT exp parsing, request wrapper, and path normalization utilities.
• Registered the driver in drivers/all.go.

Motivation and Context / 背景

• Enables OpenList to connect to 楽天ドライブ via its API for file operations and uploads.

How Has This Been Tested? / 测试

• Built and ran the Docker container locally to verify the Rakuten Drive works.

Checklist / 检查清单

• I have read the CONTRIBUTING document.
  我已阅读 CONTRIBUTING 文档。
• I have formatted my code with go fmt or prettier.
  我已使用 go fmt 或 prettier 格式化提交的代码。
• I have added appropriate labels to this PR (or mentioned needed labels in the description if lacking permissions).
  我已为此 PR 添加了适当的标签（如无权限或需要的标签不存在，请在描述中说明，管理员将后续处理）。
• I have requested review from relevant code authors using the "Request review" feature when applicable.
  我已在适当情况下使用"Request review"功能请求相关代码作者进行审查。
• I have updated the repository accordingly (If it’s needed).
  我已相应更新了相关仓库（若适用）。
• OpenList-Frontend #XXXX
• OpenList-Docs #XXXX

[ILoveScratch2]

Maybe you can extract it as a function? It was used four times.

[rufusu]

Thanks for the suggestion. Will update this to reduce duplication as well.

[dezhishen]

Would you mind moving this part into its own method? It would make the code easier to read and maintain.

[rufusu]

Thanks for the suggestion — I’ll update this to reduce duplication.

[rufusu]

refactor(rakuten_drive): extract repeated logic into helper methods

Description / 描述

• Extracted normalizePrefix method to handle directory prefix normalization logic that was repeated in Move, Rename, Copy, and Remove methods.
• Extracted detectIsFolder method to encapsulate folder detection logic from the parseList method.
• Improved code maintainability and readability by reducing code duplication.

Motivation and Context / 背景

• Addressed code review feedback requesting extraction of repeated logic into reusable methods.
• The prefix normalization pattern was duplicated 4 times across different methods.
• The folder detection logic in parseList was complex and warranted its own method for better clarity.

How Has This Been Tested? / 测试

• Verified that the code compiles without errors.
• Logic behavior remains unchanged, only code organization improved.

Checklist / 检查清单

• I have read the CONTRIBUTING document.
  我已阅读 CONTRIBUTING 文档。
• I have formatted my code with go fmt or prettier.
  我已使用 go fmt 或 prettier 格式化提交的代码。
• I have added appropriate labels to this PR (or mentioned needed labels in the description if lacking permissions).
  我已为此 PR 添加了适当的标签（如无权限或需要的标签不存在，请在描述中说明，管理员将后续处理）。
• I have requested review from relevant code authors using the "Request review" feature when applicable.
  我已在适当情况下使用"Request review"功能请求相关代码作者进行审查。
• I have updated the repository accordingly (If it's needed).
  我已相应更新了相关仓库（若适用）。
• OpenList-Frontend #XXXX
• OpenList-Docs #XXXX