A bug when files were migrated to S3

[copymonopoly]

@md-misko

Files which were migrated to S3

When uploads are migrated from local storage to S3 using the uploads:migrate_to_s3 two things happen:

• content-disposition: attachment; filename=X is set for all uploads except for images
• direct local links [dl_link](https://discourse.forum.tld/uploads/default/original/3X/0/1/0123..sha1.mp3) in raw posts are replaced with S3 links [dl_link](https://cdn_url/uploads/original/3X/0/1/0123..sha1.mp3)

This mimics the locally hosted uploads in every way (download links with original filenames as well as oneboxing).

I encountered a problem that is the opposite of what is described in this content.In fact，all files, including images, have the Content-Disposition set to attachment, causing the files to be downloaded.