Add support for the HTTP header X-Download-Options

[JaneX8]

The X-Download-Options HTTP header has only one option: X-Download-Options: noopen. This is for Internet Explorer from version 8 on to instruct the browser not to open a download directly in the browser, but instead to provide only the ‘Save’ option. The user has to first save it and then open it in an application. The reason for this is that when HTML files download from the application, the browser will render it directly inline. That means that the file renders as part of the application and has direct access to the security context of it, meaning it may run phishing attacks or maybe access critical domain cookies.

https://rorsecurity.info/portfolio/new-http-headers-for-more-security

[Malvoz]

There is a request for implementation in Edge:
https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/18488178/

However, it may be that the security issue is solved in Edge, and that the only benefit of adding this to Edge would be to allow developers to hide the "Open" button after file downloads just for the sake of hiding it.

[Loqova]

I think this needs to be documented and can be part of the security category on CanIUse.