New Feature: Add browser-level PWA install/launch/uninstall APIs (#15235)

[kblok]

Summary

Wraps Chromium's browser-scoped PWA CDP domain so you can install, launch, inspect, and uninstall Progressive Web Apps without juggling raw CDP sessions.

var manifestId = await browser.InstallPWAAsync(new InstallPWAOptions
{
    ManifestId = "https://example.com/",
    InstallUrlOrBundleUrl = "https://example.com/index.html",
    DisplayMode = PWADisplayMode.Standalone,
});

var page = await browser.LaunchPWAAsync(new LaunchPWAOptions { ManifestId = manifestId });
var state = await browser.GetPWAStateAsync(new GetPWAStateOptions { ManifestId = manifestId });
await browser.UninstallPWAAsync(new UninstallPWAOptions { ManifestId = manifestId });

A few things worth calling out:

• The PWA domain only exists over a pipe connection, so these methods require LaunchOptions.Pipe = true. It's unavailable over WebSocket.
• LaunchPWAAsync gets back a tab target id from PWA.launch, which Puppeteer doesn't expose directly through Targets() — it resolves the tab's child page target instead and returns that Page.
• BidiBrowser throws NotSupportedException for all four methods since WebDriver BiDi has no equivalent domain (matches how we handle Screens/Extensions today).

Ported from puppeteer/puppeteer#15235.

Test plan

• dotnet build on PuppeteerSharp.csproj (net8.0/net10.0/netstandard2.0) — 0 warnings, 0 errors
• New PWATests (install/uninstall, launch default url, launch explicit url, standalone display mode) pass under BROWSER=CHROME PROTOCOL=cdp
• Existing BrowserTests/ExtensionsTests still pass
• AOT JSON serialization regression test (SystemTextJsonSerializationContextTests) passes with the new PWA message types registered