feat: include prompt style in LogTheme

[alestiago]

Description

Currently, a Logger can't style the prompt with the LogTheme.

Example

void main() {
  String? style(String? text) => '>> $text';
  final Logger logger = Logger(
    theme: LogTheme(
      detail: style,
      info: style,
      err: style,
      warn: style,
      alert: style,
      success: style,
    ),
  );

  logger.prompt('hello', defaultValue: 'world');
  /// "hello (world)"
}

Requirements

• Add prompt as an option to LogTheme