Feat add remote file upload

[ZeroZ-lab]

fix #18649

Summary

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Checklist

Important

Please review the checklist below before submitting your pull request.

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

[Copilot]

Pull Request Overview

This PR implements a new remote file upload endpoint that allows files to be uploaded by specifying a remote URL and handles the associated error conditions.

• Added support for remote file uploads via a new REST API endpoint.
• Introduced new error handling via a RemoteFileUploadError and used a two-step (HEAD then GET) approach to retrieve remote file data.
• Updated the imports to include necessary modules for request parsing and remote file handling.

Files not reviewed (12)

• web/app/components/develop/template/template.en.mdx: Language not supported
• web/app/components/develop/template/template.ja.mdx: Language not supported
• web/app/components/develop/template/template.zh.mdx: Language not supported
• web/app/components/develop/template/template_advanced_chat.en.mdx: Language not supported
• web/app/components/develop/template/template_advanced_chat.ja.mdx: Language not supported
• web/app/components/develop/template/template_advanced_chat.zh.mdx: Language not supported
• web/app/components/develop/template/template_chat.en.mdx: Language not supported
• web/app/components/develop/template/template_chat.ja.mdx: Language not supported
• web/app/components/develop/template/template_chat.zh.mdx: Language not supported
• web/app/components/develop/template/template_workflow.en.mdx: Language not supported
• web/app/components/develop/template/template_workflow.ja.mdx: Language not supported
• web/app/components/develop/template/template_workflow.zh.mdx: Language not supported

[laipz8200]

#18649 (comment)