Add `show_download_button` to gr.Image() (#4959)
* add show_download_button param
* add static image story
* chlog
* fix test
* typo
* add default value
Co-authored-by: Abubakar Abid <abubakar@huggingface.co>
* fix test
* fix another test
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Co-authored-by: Abubakar Abid <abubakar@huggingface.co>
