[7.x] theme function (#73451)

[ppisljar]

Backports the following commits to 7.x:

• theme function (theme function #73451)

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: a136e63

Build metrics

@kbn/optimizer bundle module count

id	value	diff	baseline
expressions	109	+1	108

page load bundle size

id	value	diff	baseline
expressions	348.7KB	+1.2KB	347.5KB

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream