Edit state variable: system.theme.files

Add to Default shortcuts
array:8 [
  "blick" => "themes/custom/blick/blick.info.yml"
  "claro" => "core/themes/claro/claro.info.yml"
  "iframes" => "themes/custom/iframes/iframes.info.yml"
  "olivero" => "core/themes/olivero/olivero.info.yml"
  "stable9" => "core/themes/stable9/stable9.info.yml"
  "stark" => "core/themes/stark/stark.info.yml"
  "starterkit_theme" => "core/themes/starterkit_theme/starterkit_theme.info.yml"
  "widgets" => "themes/custom/widgets/widgets.info.yml"
]