More python inference snippets

[Wauplin]

Given the size of the PR and the internal changes, I think it's best to review the changes commit per commit.

This PR:

• improves snippets for document-question-answering (0288149)
• improves snippets for automated-speech-recognition (060cd21)
• adds snippets for image-to-image (6234469)
• fixes some base64 imports (0907d8f)

I added tests for all the above.
I did not add InferenceClient snippets for all tasks as it's time-consuming. I only added tasks based on the trending models listed on huggingface.co/models. We might add more tasks in the future but that's less a priority.

Also includes some cleaning:

• remove useless "export ..." from python snippets module (6d29991)
• order snippet definitions alphabetically for easier retrieval (0900c99)