Add HUB-SDK docs

[glenn-jocher]

@kalenmike @hassaanfarooq01 @sergiuwaxmann

Pending ultralytics/hub-sdk#88 merging first.

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Ultralytics removes language translation support and enhances documentation infrastructure for better maintainability and localization.

📊 Key Changes

• 💼 Workflow Adjustments: Removed Weglot translation support from the GitHub workflow.
• 🛠 Documentation Infrastructure: Added new 'Under Construction' placeholder pages and improved support for Ultralytics HUB SDK documentation.
• 📖 Improved Doc Generation: Updated the docs build process, including cloning & updating the hub-sdk repository and handling document localization better.
• 🔗 Link Fixes: Corrected links to renamed inference-api.md and updated the main navigation structure within MkDocs.
• 🔧 Code Tidying: Removed unnecessary LANGUAGES toggle and included necessary script adjustments to remove deprecated features.

🎯 Purpose & Impact

• 🏗 Build process enhancement allows for more streamlined updates and management of the Ultralytics HUB SDK documentation.
• 🧩 Removal of Weglot key support is likely to streamline the build process, but may indicate a change in how translations will be handled in the future.
• 🧰 Users will now see an 'Under Construction' placeholder for upcoming features, allowing anticipation of new releases while maintaining a clean documentation structure.
• 🔍 Corrected links and updated MkDocs navigation will provide users with an improved browsing experience and better resource discovery.
• 🧹 Code cleanup improves maintainability of the project by removing obsolete code and potentially reducing build complexity.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (67ae86f) 39.45% compared to head (9703091) 39.43%.

❗ Current head 9703091 differs from pull request most recent head e46e271. Consider uploading reports for the commit e46e271 to get more accurate results

Additional details and impacted files

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- Coverage   39.45%   39.43%   -0.02%     
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  Files         117      117              
  Lines       14392    14392              
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- Hits         5678     5676       -2     
- Misses       8714     8716       +2     

Flag	Coverage Δ
GPU	39.43% <100.00%> (-0.02%)	⬇️

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