Update whatwg/html's editor checklist to check whether new elements and attributes need to be added to the allow lists

The editor checklist is at the top of: https://raw.githubusercontent.com/whatwg/html/main/source.

The allow lists are defined at https://wicg.github.io/sanitizer-api/#constants.

[mozfreddyb]

Should we do this once the WICG spec is upstreamed into HTML or should we do a placeholder pointing to our repo in between? I am leaning to the former (and therefore waiting)

[annevk]

Yeah we should do this as part of upstreaming.