Add SDXL implementation for PyTorch/XLA training

[bhavya01]

What does this PR do?

Fixes # (issue)

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[yiyixuxu]

@bhavya01 thanks for the PR! is this ready for review?

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

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