Add cross attention type for Sana-Sprint training in diffusers. (#11514)

* test permission

* Add cross attention type for Sana-Sprint.

* Add Sana-Sprint training script in diffusers.

* make style && make quality;

* modify the attention processor with `set_attn_processor` and change `SanaAttnProcessor3_0` to `SanaVanillaAttnProcessor`

* Add import for SanaVanillaAttnProcessor

* Add README file.

* Apply suggestions from code review

* style

* Update examples/research_projects/sana/README.md

---------
Co-authored-by: lawrence-cj <cjs1020440147@icloud.com>
Co-authored-by: Sayak Paul <spsayakpaul@gmail.com>

examples/research_projects/sana/README.md

+# Training SANA Sprint Diffuser
+
+This README explains how to use the provided bash script commands to download a pre-trained teacher diffuser model and train it on a specific dataset, following the [SANA Sprint methodology](https://arxiv.org/abs/2503.09641).
+
+
+## Setup
+
+### 1. Define the local paths
+
+Set a variable for your desired output directory. This directory will store the downloaded model and the training checkpoints/results.
+
+```bash
+your_local_path='output' # Or any other path you prefer
+mkdir -p $your_local_path # Create the directory if it doesn't exist
+```
+
+### 2. Download the pre-trained model
+
+Download the SANA Sprint teacher model from Hugging Face Hub. The script uses the 1.6B parameter model.
+
+```bash
+huggingface-cli download Efficient-Large-Model/SANA_Sprint_1.6B_1024px_teacher_diffusers --local-dir $your_local_path/SANA_Sprint_1.6B_1024px_teacher_diffusers
+```
+
+*(Optional: You can also download the 0.6B model by replacing the model name: `Efficient-Large-Model/Sana_Sprint_0.6B_1024px_teacher_diffusers`)*
+
+### 3. Acquire the dataset shards
+
+The training script in this example uses specific `.parquet` shards from a randomly selected `brivangl/midjourney-v6-llava` dataset instead of downloading the entire dataset automatically via `dataset_name`.
+
+The script specifically uses these three files:
+*   `data/train_000.parquet`
+*   `data/train_001.parquet`
+*   `data/train_002.parquet`
+
+
+
+You can either:
+
+Let the script download the dataset automatically during first run
+
+Or download it manually
+
+**Note:** The full `brivangl/midjourney-v6-llava` dataset is much larger and contains many more shards. This script example explicitly trains *only* on the three specified shards.
+
+## Usage
+
+Once the model is downloaded, you can run the training script.
+
+```bash
+
+your_local_path='output' # Ensure this variable is set
+
+python train_sana_sprint_diffusers.py \
+    --pretrained_model_name_or_path=$your_local_path/SANA_Sprint_1.6B_1024px_teacher_diffusers \
+    --output_dir=$your_local_path \
+    --mixed_precision=bf16 \
+    --resolution=1024 \
+    --learning_rate=1e-6 \
+    --max_train_steps=30000 \
+    --dataloader_num_workers=8 \
+    --dataset_name='brivangl/midjourney-v6-llava' \
+    --file_path data/train_000.parquet data/train_001.parquet data/train_002.parquet \
+    --checkpointing_steps=500 --checkpoints_total_limit=10 \
+    --train_batch_size=1 \
+    --gradient_accumulation_steps=1 \
+    --seed=453645634 \
+    --train_largest_timestep \
+    --misaligned_pairs_D \
+    --gradient_checkpointing \
+    --resume_from_checkpoint="latest" \
+```
+
+### Explanation of parameters
+
+*   `--pretrained_model_name_or_path`: Path to the downloaded pre-trained model directory.
+*   `--output_dir`: Directory where training logs, checkpoints, and the final model will be saved.
+*   `--mixed_precision`: Use BF16 mixed precision for training, which can save memory and speed up training on compatible hardware.
+*   `--resolution`: The image resolution used for training (1024x1024).
+*   `--learning_rate`: The learning rate for the optimizer.
+*   `--max_train_steps`: The total number of training steps to perform.
+*   `--dataloader_num_workers`: Number of worker processes for loading data. Increase for faster data loading if your CPU and disk can handle it.
+*   `--dataset_name`: The name of the dataset on Hugging Face Hub (`brivangl/midjourney-v6-llava`).
+*   `--file_path`: **Specifies the local paths to the dataset shards to be used for training.** In this case, `data/train_000.parquet`, `data/train_001.parquet`, and `data/train_002.parquet`.
+*   `--checkpointing_steps`: Save a training checkpoint every X steps.
+*   `--checkpoints_total_limit`: Maximum number of checkpoints to keep. Older checkpoints will be deleted.
+*   `--train_batch_size`: The batch size per GPU.
+*   `--gradient_accumulation_steps`: Number of steps to accumulate gradients before performing an optimizer step.
+*   `--seed`: Random seed for reproducibility.
+*   `--train_largest_timestep`: A specific training strategy focusing on larger timesteps.
+*   `--misaligned_pairs_D`: Another specific training strategy to add misaligned image-text pairs as fake data for GAN.
+*   `--gradient_checkpointing`: Enable gradient checkpointing to save GPU memory.
+*   `--resume_from_checkpoint`: Allows resuming training from the latest saved checkpoint in the `--output_dir`.
+
+

examples/research_projects/sana/train_sana_sprint_diffusers.sh

+your_local_path='output'
+
+huggingface-cli download Efficient-Large-Model/SANA_Sprint_1.6B_1024px_teacher_diffusers  --local-dir $your_local_path/SANA_Sprint_1.6B_1024px_teacher_diffusers
+
+# or Sana_Sprint_0.6B_1024px_teacher_diffusers
+
+python train_sana_sprint_diffusers.py \
+    --pretrained_model_name_or_path=$your_local_path/SANA_Sprint_1.6B_1024px_teacher_diffusers \
+    --output_dir=$your_local_path \
+    --mixed_precision=bf16 \
+    --resolution=1024 \
+    --learning_rate=1e-6 \
+    --max_train_steps=30000 \
+    --dataloader_num_workers=8 \
+    --dataset_name='brivangl/midjourney-v6-llava' \
+    --file_path data/train_000.parquet data/train_001.parquet data/train_002.parquet \
+    --checkpointing_steps=500 --checkpoints_total_limit=10 \
+    --train_batch_size=1 \
+    --gradient_accumulation_steps=1 \
+    --seed=453645634 \
+    --train_largest_timestep \
+    --misaligned_pairs_D \
+    --gradient_checkpointing \
+    --resume_from_checkpoint="latest" \
+
+