[Feature] Suggestion: make installation easier, for example add InstallWhenNeeded

Hi,

I'm trying to get Playwright working in multiple teams. But different setup/code bases makes the installation a bit of a headache.

And then I had an idea, why don't we just make it supereasy? For example, add an option, like InstallWhenNeeded to BrowserTypeLaunchOptions that installs the browser when needed.

This will prevent then:

Executable doesn't exist
Looks like Playwright Test or Playwright was just installed or updated.
Please run the following command to download new browsers:

Proposal

My proposal, and feel free to use another name for InstallWhenNeeded

//  No install somewhere, will  do internally Program.Main(new[] { "install", "chromium" });
var browser = await playwright.Chromium.LaunchAsync();

// This should still work (manual install before launch)
Program.Main(new[] { "install", "chromium" }); 
var browser = await playwright.Chromium.LaunchAsync();

// Won't do internally Program.Main(new[] { "install", "chromium" });  - so old behavior. So crash if the browser aren't installed yet
var options = new BrowserTypeLaunchOptions { InstallWhenNeeded = false}; 
var browser = await playwright.Chromium.LaunchAsync(options);

Current work around

This is currently my work around to make things super easy:

private static async Task<IBrowser> LaunchChromiumBrowser(IPlaywright playwright, BrowserTypeLaunchOptions options)
{
    IBrowser browser;
    try
    {
        browser = await playwright.Chromium.LaunchAsync(options);
    }
    catch (PlaywrightException e) when (e.Message.Contains("Executable doesn't exist"))
    {
        Program.Main(new[] { "install", "chromium" });
        browser = await playwright.Chromium.LaunchAsync(options);
    }
    return browser;
}

Current work around - Generic version:

private static async Task<IBrowser> LaunchBrowser(IBrowserType browserType, BrowserTypeLaunchOptions options)
{
    IBrowser browser;
    try
    {
        browser = await browserType.LaunchAsync(options);
    }
    catch (PlaywrightException e) when (e.Message.Contains("Executable doesn't exist"))
    {
        Program.Main(new[] { "install", browserType.Name });
        browser = await browserType.LaunchAsync(options);
    }
    return browser;
}

And yes, it make the first test slow. But if that's an issue, you could still install it manually like before.

related:
#990, #1692,#1793, #1822, #2006, #2181, #2198

Start by reading BrowserTypeLaunchOptions and the IBrowserType LaunchAsync entry points, then review the related issues #990, #1692, #1793, #1822, #2006, #2181 and #2198. Compare the proposed automatic installation behavior with the existing install command and manual-launch workaround. Done means the behavior and opt-out semantics are defined and covered for Chromium and generic browser types.