Iterative generation using Input embeds and past_key_values (#35890)

* Iterative generation using input embeds

* ruff fix

* Added Testcase

* Updated comment

* ♻️ Refactored testcase

* Skip test for these models

* Continue generation using input embeds and cache

* Skip generate_continue_from_embeds test

* Refactor `prepare_input_for_generation` func

* Continue generation using input embeds and cache

* Modular changes fix

* Overwrite 'prepare_inputs_for_generation' function

tests/models/fuyu/test_modeling_fuyu.py

@@ -325,6 +325,10 @@ class FuyuModelTest(ModelTesterMixin, GenerationTesterMixin, PipelineTesterMixin
     def test_model_parallelism(self):
         super().test_model_parallelism()
 
+    @unittest.skip(reason="Fuyu `prepare_inputs_for_generation` function doesn't have cache position.")
+    def test_generate_continue_from_inputs_embeds():
+        pass
+
 
 @slow
 @require_torch_accelerator