[model] add Qwen2.5-Omni model (#7537)

* preserve image_sizes

* preserve image_sizes

* init plugin

* support audio-text2text lora

* nit

* support image/video-text2text, audio-text2text

* remove args

* remove lines

* add docs && nit

* remove some comments

* fix && add merge part script

* add license

src/llamafactory/extras/constants.py

@@ -2270,6 +2270,18 @@ register_model_group(
 )
 
 
+register_model_group(
+    models={
+        "Qwen2.5-Omni-7B": {
+            DownloadSource.DEFAULT: "Qwen/Qwen2.5-Omni-7B",
+            DownloadSource.MODELSCOPE: "Qwen/Qwen2.5-Omni-7B",
+        }
+    },
+    template="qwen2_omni",
+    multimodal=True,
+)
+
+
 register_model_group(
     models={
         "Qwen2-VL-2B": {