KSES: Allow HTML data-* attributes.

Add global support for HTML attributes prefixed `data-` for authors and contributors, as required by the new editor.

Merges [43727] to trunk.

Props azaozz, peterwilsoncc.
Fixes #33121.

Built from https://develop.svn.wordpress.org/trunk@43981


git-svn-id: https://core.svn.wordpress.org/trunk@43813 1a063a9b-81f0-0310-95a4-ce76da25c4cd