Do not inject WordPress styles when not the active theme
When the Extension is active but the theme is not selected as the back-end theme, the inline WordPress styles are still loaded. This MR fixes this.
You may want to review the check for whether or not the theme is active - the current check via _theisland_isActive()
seems not to give consistent results whereas checking via API4 does. If you'd prefer to stick with the current check, please go ahead... it's really the code in theisland_civicrm_config()
that matters most.