IDEFICS: support inputs embeds (#34043)

* support embeds

* use cache from config

* style...

* fix tests after rebase

tests/models/kosmos2/test_modeling_kosmos2.py

@@ -428,6 +428,12 @@ class Kosmos2ModelTest(ModelTesterMixin, PipelineTesterMixin, unittest.TestCase)
             # self.assertTrue(model.transformer.wte.weight.shape, model.lm_head.weight.shape)
             # self.assertTrue(check_same_values(model.transformer.wte, model.lm_head))
 
+    @unittest.skip(
+        "KOSMOS-2 doesn't support inputs embeds. The test isn't skipped by checking ipnut args because KOSMOS-2 has `generate()` overwritten"
+    )
+    def test_inputs_embeds_matches_input_ids_with_generate(self):
+        pass
+
     @slow
     def test_model_from_pretrained(self):
         model_name = "microsoft/kosmos-2-patch14-224"