[WIP] Support BLIP and GIT in image-to-text and VQA pipelines
# What does this PR do?
Support BLIP and GIT models in image-to-text and VQA pipelines.

Fixes #21110 


## Before submitting
- [ ] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
- [ ] Did you read the [contributor guideline](https://github.com/huggingface/transformers/blob/main/CONTRIBUTING.md#start-contributing-pull-requests),
      Pull Request section?
- [ x] Was this discussed/approved via a Github issue or the [forum](https://discuss.huggingface.co/)? Please add a link
      to it if that's the case.
- [ ] Did you make sure to update the documentation with your changes? Here are the
      [documentation guidelines](https://github.com/huggingface/transformers/tree/main/docs), and
      [here are tips on formatting docstrings](https://github.com/huggingface/transformers/tree/main/docs#writing-source-documentation).
- [ ] Did you write any new necessary tests?


## Who can review?
@NielsRogge 

The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_21227). All of your documentation changes will be reflected on that endpoint.<|||||>Hi @NielsRogge, should I remove the return of the topk scores in the VQA pipeline that used ViltForQuestionAnswering only?<|||||>This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

Please note that issues that do not follow the [contributing guidelines](https://github.com/huggingface/transformers/blob/main/CONTRIBUTING.md) are likely to be ignored.