Convert 'mark' theme hook to a suggestion of html_tag

Follow-up to #1939092: Convert theme_mark() to Twig →

Blocked on: #939462: Specific preprocess functions for theme hook suggestions are not invoked →

Problem/Motivation

• The mark theme hook is really just a "tag" with "attributes" and a "value" (one line, more or less, template)
• The mark theme hook is not extensible (cannot add classes via a preprocess function, must override the template).

Proposed resolution

• Convert all invocations of '#theme' => 'mark' to '#type' => 'html_tag__mark'
• Move data logic from the template to a preprocess function.
• Populate the attributes array with the correct classes (based on constants currently).

Remaining tasks

• Create patch

User interface changes

None

API changes

Conversion of a theme hook into a different theme hook suggestion?