Add "charset" to Content-Type header when uploading HTML files to S3

[cyberduck]

David (3) created the issue

There should be a way for a user to indicate to Cyberduck that all HTML files uploaded to S3 should have a certain character set (most likely utf-8) applied to them. This should set the Content-Type header of the uploaded file to "text/html; charset=utf-8" rather than the normal "text/html". Ideally, the character set should be auto-detected, but in practice that is difficult to do reliably.

[cyberduck]

@dkocher commented

Duplicate for #5364.