Update serving code to enable saved_model=True (#18153)

* Add serving_output and serving methods to some vision models

* Add serving outputs for DeiT

* Don't convert hidden states - differing shapes

* Make saveable

* Fix up

* Make swin saveable

* Add in tests

* Fix funnel tests (can't convert to tensor)

* Fix numpy call

* Tidy up a bit

* Add in hidden states - resnet

* Remove numpy

* Fix failing tests - tensor shape and skipping tests

* Remove duplicated function

* PR comments - formatting and var names

* PR comments
Add suggestions made by Joao Gante:
* Use tf.shape instead of shape_list
* Use @tooslow decorator on tests
* Simplify some of the logic

* PR comments
Address Yih-Dar Sheih comments - making tensor names consistent and make types float

* Types consistent with docs; disable test on swin (slow)

* CI trigger

* Change input_features to float32

* Add serving_output for segformer

* Fixup

Co-authored-by: Amy Roberts <amyeroberts@users.noreply.github.com>

tests/models/led/test_modeling_tf_led.py

@@ -17,7 +17,7 @@
 import unittest
 
 from transformers import LEDConfig, is_tf_available
-from transformers.testing_utils import require_tf, slow
+from transformers.testing_utils import require_tf, slow, tooslow
 
 from ...test_configuration_common import ConfigTester
 from ...test_modeling_tf_common import TFModelTesterMixin, ids_tensor
@@ -365,8 +365,8 @@ class TFLEDModelTest(TFModelTesterMixin, unittest.TestCase):
         # TODO JP: Make LED XLA compliant
         pass
 
+    @tooslow
     def test_saved_model_creation(self):
-        # This test is too long (>30sec) and makes fail the CI
         pass
 
     def test_generate_with_headmasking(self):