[Plugin API Request] Filter `x-frame-options` HTTP header for plugin's HTTP request

Background: I want to accomplish a feature like previewing web page with <iframe> when hovering on <a>. Some websites' HTTP response headers includes x-frame-options so <iframe> fail.

Request: FIlter out this HTTP Header for markdown view and plugin's webviews. See

Common users will also be benefitted from this because they will be able to use <iframe> in their markdown.