fix(doc-api): gate textStyle attrs and sync reference coverage#2430

harbournick merged 3 commits intomainsuperdoc-dev/superdoc:mainfrom

nick/sd-2074-bug-formatletterspacing-no-ops-in-docapi-harness-no-xmlsuperdoc-dev/superdoc:nick/sd-2074-bug-formatletterspacing-no-ops-in-docapi-harness-no-xmlCopy head branch name to clipboard