[Feat] Diffusion Model(PixArtAlpha/StableDiffusion3) Support (#5838)

* Diffusion Model Inference support

* Stable Diffusion 3 Support

* pixartalpha support

colossalai/inference/struct.py

@@ -2,6 +2,7 @@ import enum
 from dataclasses import dataclass
 from typing import Any, List
 
+from colossalai.inference.config import DiffusionGenerationConfig
 from colossalai.logging import get_dist_logger
 
 logger = get_dist_logger(__name__)
@@ -46,6 +47,17 @@ class RequestStatus(enum.Enum):
         return status == RequestStatus.WAITING
 
 
+@dataclass
+class DiffusionSequence:
+    """
+    parameters for diffusion
+    """
+
+    request_id: int
+    prompt: str
+    generation_config: DiffusionGenerationConfig
+
+
 @dataclass
 class Sequence:
     """Store information of input sequence.