Make Fetcher public

[Subhra264]

The fetch method of Fetcher looks for existing chrome installations, otherwise installs one which is cool. But if I am not missing anything, there is no public function that makes the fetch function available for use. The fetch function is called intenally only when Browser::new() is called.

So, suppose we have a REST Rust server and there is an API to generate some report. The API request handler internally uses headless chrome and launches browser for each request. Then the first request will wait until Browser::new installs chrome.

If Fetcher is public, then I don't need to use Browser::new() for the installation. Instead, I can pass env configurations to the server initializer function and install chrome while setting up the server only -

/// A global static launchoptions settings
pub static CHROME_LAUNCHER_OPTIONS: Lazy<LaunchOptions<'_>> = Lazy::new(|| {
        let mut options = LaunchOptions::default_builder();
        options
            .window_size(Some((
                CONFIG.chrome.chrome_window_width,
                CONFIG.chrome.chrome_window_height,
            )))
            .enable_logging(CONFIG.chrome.chrome_enable_logging)
            .idle_browser_timeout(Duration::from_secs(
                CONFIG.chrome.chrome_idle_timeout.into(),
            ));

        if !CONFIG.chrome.chrome_path.is_empty() {
            options.path(Some(CONFIG.chrome.chrome_path.clone().into()));
        }

        let mut options = options.build().unwrap();
        // Install chrome executable now and not while creating browser instance
       if options.path.is_none() {
            let fetch = Fetcher::new(options.fetcher_options.clone());
            options.path = Some(fetch.fetch().unwrap());
        }
        options
});