Add PixArt support

[JingyaHuang]

What does this PR do?

• PixArt export support Alpha via CLI

• Tiny

optimum-cli export neuron --model hf-internal-testing/tiny-pixart-alpha-pipe --batch_size 1 --height 64 --width 64 --num_images_per_prompt 1 --torch_dtype bfloat16 --sequence_length 32 pixart_alpha_neuron_tiny/

• Regular

optimum-cli export neuron --model PixArt-alpha/PixArt-XL-2-512x512 --batch_size 1 --height 512 --width 512 --num_images_per_prompt 1 --torch_dtype bfloat16 --sequence_length 120 pixart_alpha_neuron_512/

• PixArt export support Alpha via API

import torch
from optimum.neuron import NeuronPixArtAlphaPipeline

# Compile
model_id = "PixArt-alpha/PixArt-XL-2-512x512"
compiler_args = {"auto_cast": "none"}
input_shapes = {"batch_size": 1, "height": 512, "width": 512, "sequence_length": 120}

neuron_model = NeuronPixArtAlphaPipeline.from_pretrained(model_id, torch_dtype=torch.bfloat16, export=True, disable_neuron_cache=True, **compiler_args, **input_shapes)

# Save locally or upload to the HuggingFace Hub
save_directory = "pixart_alpha_neuron_512/"
neuron_model.save_pretrained(save_directory)

• Caching support
• PixArt inference support

from optimum.neuron import NeuronPixArtAlphaPipeline

# Inference
neuron_model = NeuronPixArtAlphaPipeline.from_pretrained("pixart_alpha_neuron_512/")
prompt = "An astronaut riding a green horse"
image = neuron_model(prompt=prompt).images[0]
image.save("out.png")

• Tests
• Documentation

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• Did you make sure to update the documentation with your changes?
• Did you write any new necessary tests?

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

[github-actions]

This PR is stale because it has been open 15 days with no activity. Remove stale label or comment or this will be closed in 5 days.

[github-actions]

This PR is stale because it has been open 15 days with no activity. Remove stale label or comment or this will be closed in 5 days.

[michaelbenayoun]

Not very knowleadgeable on this part, but lgtm!

[dacorvo]

LGTM, thanks !