💡Allow skipping of on-page content styles, or avoid them altogether

I'm hoping to use editor.js for editing already-styled content, versus the generic styles that are built in. Using editor.js in an iframe helps isolate styles, but editor.js includes tags in the header that include generic content styles, like `.ce-header`, `.cdx-list--unordered`, and `.cdx-list` and these override my already-styled content.

The documentation mentions that the styles can be overridden, but since they're on-page <style> tags, they override my already-styled link css, and without me using !important or manually overriding styles on-page, it's not easy to use. (At the same time, the context menu and other function styles are very useful, of course, I'm only suggesting the content styling to be removable.)

A solution could be `skipContentStyles: true` in the config would be one solution, or just not styling the content parts at all, leaving the user to choose their own or the browser's default.