Expand allowable set of custom data attribute names to include those containing
leading, trailing, and double `-` characters. Previously, WordPress was
removing data attributes that are used in the Interactivity API. By allowing
these additional custom data attributes, the related Interactivity API
directives will preserve through `kses`.
For example, the Interactivity API frequently relies on custom data attributes
such as `data-wp-on--click="..."`. The change in [43981] would strip these out
of the processed HTML, however.
Developed in https://github.com/WordPress/wordpress-develop/pull/6598
Discussed in https://core.trac.wordpress.org/ticket/61052
Props cbravobernal, dmsnell, gziolo, jonsurrell.
Follow-up to [43981].
Fixes#61052.
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