Feat: Convert images in pdfs to images that can be accessed by the user

[calebpeffer]

Some customers want to access images inside PDFs on the web. I'm not sure if llama-index supports this by default?

If we can get the images, we may need to start hosting ourselves in S3 too. This is probably a better solution for ALL images, since people should be cleaning out links to images on external URLs because of data exfil problems.