deprecated-element

Split into no-obsolete-element (error, HTML LS removed elements) and no-deprecated-element (warning, MDN/BCD). The alias copies the old setting to both until v6.

v4 deprecated-element defaulted to error for both kinds. In v5 only obsolete stays error.

This rule never checked non-standard elements. That check is the new no-nonstandard-features rule (not present in v4). See Renames and splits.