Allow macros to declare search keywords for Quick Actions and the Insert Macro dialog

The WYSIWYG usability audit of the macros records the missing synonyms of each macro under the criterion D4 quick-action, and this issue is mapped as covering all of them. We won't report one issue per macro for now: if the community agrees on this new feature, we'll then report, for each macro, the search keywords it should declare, based on the synonyms listed on its audit page.