Renders a <link rel="icon"> tag driven by the PhoenixKit site_icon_file_uuid
setting.
Parent applications should include this component inside their root layout's
<head> so the site icon uploaded via PhoenixKit Settings actually reaches
the browser tab. PhoenixKit's standalone admin layout already includes it.
If the setting is empty, the component renders nothing so the parent app's static favicon keeps working.
Usage
<head>
...
<PhoenixKitWeb.Components.Core.PhoenixKitFavicon.phoenix_kit_favicon />
</head>