Expand inputs in processors for VLMs (#30962)

* let it be

* draft

* should not have changed

* add warnings

* fix & add tests

* fix tests

* ipnuts embeds cannot be passed with pixels

* more updates

* paligemma ready!

* minor typos

* update blip-2

* fix tests & raise error

* docstring

* add blip2 test

* tmp

* add image seq length to config

* update docstring

* delete

* fix tests

* fix blip

* fix paligemma

* out-of-place scatter

* add llava-next-video

* Update src/transformers/models/blip_2/modeling_blip_2.py

Co-authored-by: Pablo Montalvo <39954772+molbap@users.noreply.github.com>

* remove tmp

* codestyle

* nits

* more nits

* remove overriding in tests

* comprehension when merging video

* fix-copies

* revert changes for embeds test

* fix tests after making comprehension

* Update src/transformers/models/blip_2/processing_blip_2.py

Co-authored-by: Pablo Montalvo <39954772+molbap@users.noreply.github.com>

* Update src/transformers/models/blip_2/processing_blip_2.py

Co-authored-by: Pablo Montalvo <39954772+molbap@users.noreply.github.com>

* more updates

* fix tests

---------

Co-authored-by: Pablo Montalvo <39954772+molbap@users.noreply.github.com>

tests/models/instructblip/test_processor_instructblip.py

@@ -119,7 +119,7 @@ class InstructBlipProcessorTest(unittest.TestCase):
             tokenizer=tokenizer, image_processor=image_processor, qformer_tokenizer=qformer_tokenizer
         )
 
-        input_str = "lower newer"
+        input_str = ["lower newer"]
 
         encoded_processor = processor(text=input_str)