Attention masks are missing in SD3 to mask out text padding tokens

### Describe the bug

In the attention implementation of SD3, attention masks currently are not used. This will result in inconsistent outputs for the different values `max_seq_length` where padding exists in text tokens as the attention scores of padding tokens are non-zero. This issue has been discussed in https://github.com/huggingface/diffusers/discussions/8628, and is created to track the progress of fixing this problem.

Thanks @sayakpaul for the discussion.

### Reproduction

n/a

### Logs

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### System Info

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### Who can help?

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