In conformance with the requirements of the spec PR at
https://github.com/whatwg/html/pull/9546, this change adds support for
the “switch” attribute for type=checkbox “input” elements — which is
shipping in Safari (since Safari 17.4). This change also implements
support for exposing it to AT users with role=switch.
Compared to version 10 this fixes a bunch of formatting issues, mostly
around structs/classes with attributes like [[gnu::packed]], and
incorrect insertion of spaces in parameter types ("T &"/"T &&").
I also removed a bunch of // clang-format off/on and FIXME comments that
are no longer relevant - on the other hand it tried to destroy a couple of
neatly formatted comments, so I had to add some as well.
