1. Add some "render-content" classes to "markup" elements when the
content is rendered
2. Use correct "markup" wrapper for "preview" (but not set that class on
the tab)
3. Remove incorrect "markup" class from LFS file view, because there is
no markup content
* "edit-diff" is also removed because it does nothing
5. Use "initPdfViewer" for PDF viewer
6. Remove incorrect "content" class from milestone markup
7. Init all ".markup" elements by new init framework
---------
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
None of the frontend js/ts files was touched besides these two commands
(edit: no longer true, I touched one file in
61105d0618
because of a deprecation that was not showing before the rename).
`tsc` currently reports 778 errors, so I have disabled it in CI as
planned.
Everything appears to work fine.
