createWidget function
river_cli create widget:<name>
Implementation
void createWidget(CreateOptions opts, ProjectContext ctx) {
final snake = Naming.snake(opts.name);
final dir = ctx.hasWidgets ? 'lib/app/shared_widgets' : 'lib/widgets';
final writer = FileWriter(force: opts.force, dryRun: opts.dryRun);
print('Creating widget: ${Naming.pascal(opts.name)}');
writer.write('$dir/$snake.dart', widgetTemplate(opts.name, ctx));
writer.printSummary();
}