Add download client customizable url base (#43)

code/Common/Configuration/DownloadClient/QBitConfig.cs

@@ -1,4 +1,5 @@
-using Common.Exceptions;
+using Common.Exceptions;
+using Microsoft.Extensions.Configuration;
 
 namespace Common.Configuration.DownloadClient;
 
@@ -8,6 +9,9 @@ public sealed class QBitConfig : IConfig
     
     public Uri? Url { get; init; }
     
+    [ConfigurationKeyName("URL_BASE")]
+    public string UrlBase { get; init; } = string.Empty;
+    
     public string? Username { get; init; }
     
     public string? Password { get; init; }