[Spec Decode] Add hidden states extraction system (#33736)

Signed-off-by: Fynn Schmitt-Ulms <fschmitt@redhat.com>

tests/models/registry.py

@@ -108,7 +108,7 @@ class _HfExamplesInfo:
 
     use_original_num_layers: bool = False
     """
-    If True, use the original number of layers from the model config 
+    If True, use the original number of layers from the model config
     instead of minimal layers for testing.
     """
 
@@ -1156,6 +1156,10 @@ _SPECULATIVE_DECODING_EXAMPLE_MODELS = {
         speculative_model="LGAI-EXAONE/K-EXAONE-236B-A23B",
         min_transformers_version="5.1.0",
     ),
+    "ExtractHiddenStatesModel": _HfExamplesInfo(
+        "Qwen/Qwen3-8B",
+        speculative_method="extract_hidden_states",
+    ),
     "Glm4MoeMTPModel": _HfExamplesInfo(
         "zai-org/GLM-4.5",
         speculative_model="zai-org/GLM-4.5",