Mutation.publishTheme
Snapshot + flip the theme's published_files_version_id to point at the new snapshot. Optionally promote to 'main' (live).
ReturnsThemeVersion!
Signature
Snapshot + flip the theme's published_files_version_id to point at the new snapshot. Optionally promote to 'main' (live).
theme_idID!labelStringbecome_mainBoolean