Major VLM tracker (standardize the API)

### Feature request This will track general plans on VLM and composite models so that we can align with work in TGI and other libraries. I already have some trackers so in this one I'll lay out a more bigger picture with links to respective discussions/topics ### Motivation We already have a pretty good working standards when it comes to language models, and when adding a new model usually a few "copy from" statements will do the work. We also cover most cases for LMs in out test suite. But for wave of multimodal models we still lack any form of standardization and uniform API. Each new model added to the library introduces something new, that forces us to accept it as is until we figure out how to handle it later So we need to try to standardize those models, currently starting from VLMs. VLMs are the most commonly added models currently, but we may have more audio+text or pure multimodal ones in the future. For now we start off by working on VLM and see how things fit in the general API ### Your contribution The major changes we are working on and planning to work are: - Standardization for Processors: - We have ongoing work on uniform processor kwargs which currently will help us enable pipelines for VLMs and thus we can have correct automodel tag on the hub. The work is under progress by @yonigozlan and @molbap - Parallel to that I will work on separating out video models under a new class (VideoProcessor) and handling a whole lot of deprecation cycle for the processing config files. At the end we should have separate file/separate class for video processing and save its params in its own config file. That will be tracked in https://github.com/huggingface/transformers/issues/33504 and has discussions with Amy in the linked issue under that - Standardization in terms of modeling code: - One major thing was to get rid of buggy `merge_embeds` method and cover VLMs with more generation related tests, as we were getting many issues after a small change. …