load static method
Load a theme from the assets by name.
The theme file should be located at assets/themes/$themeName.json.
Implementation
static Future<FluffyThemeData> load(String themeName) async {
final themeData = await rootBundle.loadString(
'assets/themes/$themeName.json',
cache: false,
);
final themeJson = jsonDecode(themeData) as Map<String, dynamic>;
return FluffyThemeData.fromJson(themeJson);
}