feat(backend): Support GPU TP and enable TP for non-scheduler mode

[TianyiZhao1437]

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📝 Change Type

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• feat: New feature.
• fix: Bug fix.
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💡 Description

Support GPU inter-node tensor parallelism.

Key Changes

1. Backend supports GPU TP.
2. Launches each TP executor in subprocess. However, since we need to refactor the inter-process communication with gradient server, this feature is currently only enabled in non-scheduler mode.

🔗 Related Issues

List any issues this PR closes or relates to:

• Relates to [Feature]: Support TP on gpu #152

✅ Checklist

Please ensure the following points are addressed before merging:

• I have performed a self-review of my own code.
• I have added/updated tests that prove my fix or feature works (if applicable).
• I have updated the documentation (if necessary).
• My code follows the project's style guidelines.