[generate] shape checks in tests compatible with fixed-length caches (+ some minor fixes) (#35993)

* shape checks compatible with static cache

* add test

* tmp

* manually turn on eager attn when we want to output attn

* typo

* generalize to encoder-decoder models

* force compilation on cpu

* tmp commit

* fix static cache shape checks

* models with odd caches

* fix copies

* shorter cache search loop

* use decoder_past_key_values everywhere

* better test variable names and comments

* signature

* rename _check_outputs into _check_generate_outputs

* add comments

* HybridCache future test note

tests/models/whisper/test_modeling_whisper.py

@@ -1607,6 +1607,11 @@ class WhisperModelTest(ModelTesterMixin, GenerationTesterMixin, PipelineTesterMi
     def test_generate_compile_model_forward(self):
         pass
 
+    # TODO (joao, eustache): fix me :)
+    @unittest.skip(reason="A CUDA exception is thrown when storing extra outputs")
+    def test_generate_compilation_all_outputs(self):
+        pass
+
 
 @require_torch
 @require_torchaudio