DownloadClient and MangaConnector improvements

DownloadClient is now abstract for HttpDownloadClient and ChromiumDownloadClient
The chromium client will exit the headless browser (on clean exit of the program).
The field "name" of MangaConnector is no longer abstract, instead set through constructor.

Tranga/MangaConnectors/HttpDownloadClient.cs

@@ -0,0 +1,70 @@
+using System.Net.Http.Headers;
+using HtmlAgilityPack;
+
+namespace Tranga.MangaConnectors;
+
+internal class HttpDownloadClient : DownloadClient
+{
+    private static readonly HttpClient Client = new()
+    {
+        Timeout = TimeSpan.FromSeconds(60),
+        DefaultRequestHeaders =
+        {
+            UserAgent =
+            {
+                new ProductInfoHeaderValue("Tranga", "0.1")
+            }
+        }
+    };
+
+
+    public HttpDownloadClient(GlobalBase clone, Dictionary<byte, int> rateLimitRequestsPerMinute) : base(clone, rateLimitRequestsPerMinute)
+    {
+        
+    }
+    
+    protected override RequestResult MakeRequestInternal(string url, string? referrer = null)
+    {
+        HttpResponseMessage? response = null;
+        while (response is null)
+        {
+            HttpRequestMessage requestMessage = new(HttpMethod.Get, url);
+            if (referrer is not null)
+                requestMessage.Headers.Referrer = new Uri(referrer);
+            //Log($"Requesting {requestType} {url}");
+            response = Client.Send(requestMessage);
+        }
+
+        if (!response.IsSuccessStatusCode)
+        {
+            Log($"Request-Error {response.StatusCode}: {response.ReasonPhrase}");
+            return new RequestResult(response.StatusCode,  null, Stream.Null);
+        }
+        
+        Stream stream = response.Content.ReadAsStream();
+
+        HtmlDocument? document = null;
+
+        if (response.Content.Headers.ContentType?.MediaType == "text/html")
+        {
+            StreamReader reader = new (stream);
+            document = new ();
+            document.LoadHtml(reader.ReadToEnd());
+            stream.Position = 0;
+        }
+
+        // Request has been redirected to another page. For example, it redirects directly to the results when there is only 1 result
+        if (response.RequestMessage is not null && response.RequestMessage.RequestUri is not null)
+        {
+            return new RequestResult(response.StatusCode, document, stream, true,
+                response.RequestMessage.RequestUri.AbsoluteUri);
+        }
+
+        return new RequestResult(response.StatusCode, document, stream);
+    }
+
+    public override void Close()
+    {
+        Log("Closing.");
+    }
+}