This is a pure git rename in order to make sure that git can follow
history. The next commit will integrate these into mdbook-html.
Additional commits will refactor/move/remove items.
This fixes several issues with how the sidebar was behaving:
- Manually resizing the sidebar was incorrectly applying transition
animations to the page-wrapper causing awkward movement.
- Clicking the sidebar toggle caused the menu bar to behave differently
compared to loading a page with the sidebar visible or hidden.
- page-wrapper animation wasn't working when JS was disabled.
- RTL sidebar animation was broken.
Most of these issues stem from
https://github.com/rust-lang/mdBook/pull/2454 which moved `js` and
`sidebar-visible` classes from `<body>` to `<html>`, but failed to
update some of the JS and CSS code that was still assuming it was on the
body.
https://github.com/rust-lang/mdBook/pull/1641 previously moved `js` from
`<html>` to `<body>` with the reasoning
"This will be necessary for using CSS selectors on root attributes.".
However, I don't see how that is absolutely necessary, since selectors
like `[dir=rtl].js` should work to select the root element.
