[trainer] feat: add CI for accuracy alignment of SFT trainer with model engine

[vermouth1992]

What does this PR do?

• Add CI for SFT trainer with various fsdp and megatron configurations and make sure their output matches

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[gemini-code-assist]

Code Review

This pull request introduces a CI test to ensure numerical accuracy alignment for the SFT trainer across various FSDP and Megatron configurations. The changes are comprehensive, including parameterizing test scripts, adding a file-based logger for result comparison, and, most importantly, aligning the loss scaling logic in both FSDP and Megatron engines to correctly handle dynamic batch sizes and gradient accumulation. The modifications to the learning rate scheduler also contribute to this alignment. Overall, this is a strong contribution to improving the robustness and reliability of the training framework. I have a couple of suggestions to improve the robustness of the new FileLogger.