[platform] Support additional forward context for OOT (#31674)

Signed-off-by: zzzzwwjj <1183291235@qq.com>
Signed-off-by: zzzzwwjj <34335947+zzzzwwjj@users.noreply.github.com>
Co-authored-by: Cyrus Leung <cyrus.tl.leung@gmail.com>

vllm/platforms/interface.py

@@ -693,6 +693,13 @@ class Platform:
         """
         return max_model_len
 
+    @classmethod
+    def set_additional_forward_context(cls, *args, **kwargs) -> dict[str, Any]:
+        """
+        Set some additional forward context for the current platform if needs.
+        """
+        return {}
+
 
 class UnspecifiedPlatform(Platform):
     _enum = PlatformEnum.UNSPECIFIED