fix: prevent infinite hang on package loading when NCSI is stale

[Zeroes1]

Add 30s timeout and HTTP fallback to internet connectivity check.

Problem: UniGetUI hangs indefinitely (20+ minutes) on the "Loading packages" screen when scanning installed packages. The root cause is _waitForInternetConnection() which uses NetworkInformation.GetInternetConnectionProfile() (NCSI) to check connectivity. On Windows 10, NCSI frequently returns null or NoInternetAccess even when the internet is actually working (known NCSI bug). The function has no timeout, causing an infinite loop.

Fix (Tools.cs:_waitForInternetConnection):

Added a 30-second timeout. After the timeout expires, the function logs a warning and proceeds — it no longer blocks package loading indefinitely.
Added an HTTP fallback: a HEAD request to http://msftconnecttest.com/connecttest.txt with a 5-second timeout. If NCSI incorrectly reports "no internet" (common Win10 bug) but the HTTP request succeeds, the connection is considered available.
Replaced the infinite while loop with a bounded for loop with a maximum iteration count.

close #3669

[Gabriel Dufresne (GabrielDuf)]

Hi Zeroes1,
There are a few warnings because WebRequest.Create(string) is now obsolete. Could you please take a look?

[Kobi-Blade]

Hi Zeroes1, There are a few warnings because WebRequest.Create(string) is now obsolete. Could you please take a look?

Hi Gabriel, if you look into this, you can simplify the entire method massively using HttpClient. It is cross-platform and would fix the warnings.

public static async Task WaitForInternetConnectionAsync(
    int retryDelayMs = 1000,
    int maxRetries = 300
)
{
    if (Settings.Get(Settings.K.DisableWaitForInternetConnection))
        return;

    Logger.Debug("Checking for internet connectivity...");
    bool warned = false;

    using HttpClient client = new HttpClient
    {
        Timeout = TimeSpan.FromSeconds(3)
    };

    for (int attempt = 0; attempt < maxRetries; attempt++)
    {
        try
        {
            using var response = await client.SendAsync(
                new HttpRequestMessage(HttpMethod.Head, "http://connectivitycheck.gstatic.com/generate_204"),
                HttpCompletionOption.ResponseHeadersRead
            );

            if (response.IsSuccessStatusCode)
            {
                Logger.Debug("Internet connectivity was established.");
                return;
            }
        }
        catch
        {

        }

        if (!warned)
        {
            Logger.Warn(
                "User is not connected to the internet, waiting for an internet connection to be available..."
            );
            warned = true;
        }

        await Task.Delay(retryDelayMs);
    }

    Logger.Error("Internet connection could not be established within the allowed time.");
}