[browser][http] Fix HttpClientHandler "Supports*" properties regressions

[kjpou1]

Also needs implementing on SocketsHttpHandler which will default to true.

        internal bool SupportsAutomaticDecompression => true;
        internal bool SupportsProxy => true;
        internal bool SupportsRedirectConfiguration => true;

Fix #39760

[ghost]

Tagging subscribers to this area: @dotnet/ncl
See info in area-owners.md if you want to be subscribed.

[kjpou1]

@marek-safar | @lewing | @stephentoub could someone take a look

[marek-safar]

Looks good to me, can anyone from @dotnet/ncl review the change ?

[scalablecory]

Change looks fine.

For the future, our code for automatic decompression and redirect handling is handler-agnostic and might easily be integrated into BrowserHttpHandler. See how SocketsHttpHandler sets them up here by layering handlers:

runtime/src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/SocketsHttpHandler.cs

Lines 290 to 334 in 809a06f

	private HttpMessageHandlerStage SetupHandlerChain()
	{
	// Clone the settings to get a relatively consistent view that won't change after this point.
	// (This isn't entirely complete, as some of the collections it contains aren't currently deeply cloned.)
	HttpConnectionSettings settings = _settings.CloneAndNormalize();
	HttpConnectionPoolManager poolManager = new HttpConnectionPoolManager(settings);
	HttpMessageHandlerStage handler;
	if (settings._credentials == null)
	{
	handler = new HttpConnectionHandler(poolManager);
	}
	else
	{
	handler = new HttpAuthenticatedConnectionHandler(poolManager);
	}
	if (settings._allowAutoRedirect)
	{
	// Just as with WinHttpHandler, for security reasons, we do not support authentication on redirects
	// if the credential is anything other than a CredentialCache.
	// We allow credentials in a CredentialCache since they are specifically tied to URIs.
	HttpMessageHandlerStage redirectHandler =
	(settings._credentials == null || settings._credentials is CredentialCache) ?
	handler :
	new HttpConnectionHandler(poolManager); // will not authenticate
	handler = new RedirectHandler(settings._maxAutomaticRedirections, handler, redirectHandler);
	}
	if (settings._automaticDecompression != DecompressionMethods.None)
	{
	handler = new DecompressionHandler(settings._automaticDecompression, handler);
	}
	// Ensure a single handler is used for all requests.
	if (Interlocked.CompareExchange(ref _handler, handler, null) != null)
	{
	handler.Dispose();
	}
	return _handler;
	}

[kjpou1]

@scalablecory Those two things are taken care of via the browser's fetch implementation such that we do not have control of the functionality. Really outside of the domain we can touch or control.