[code-watcher] Add CodeWatcherMode option.

There are three option values:
- Disabled: module does nothing (wow).
- Remove: module removes matching messages and sends temporary message
          to instruct user what to do.
- Upload: module uploads detected code to configured Haste Server.

modules/CodeWatcher/CodeWatcher.cs

@@ -1,9 +1,23 @@
 using Kruzya.TelegramBot.Core;
+using Kruzya.TelegramBot.Core.Extensions;
+using Microsoft.Extensions.DependencyInjection;
+using West.TelegramBot.CodeWatcher.Options;
+using West.TelegramBot.CodeWatcher.Service;
 
 namespace West.TelegramBot.CodeWatcher
 {
     public class CodeWatcher : Module
     {
         public CodeWatcher(Core core) : base(core) {}
+
+        public override void ConfigureServices(IServiceCollection services)
+        {
+            services.AddOption<CodeWatcherMode>();
+            
+            services.AddHttpClient<IHasteService, HasteService>(c =>
+            {
+                c.BaseAddress = new Uri(Core.Configuration["HastebinUrl"]!);
+            });
+        }
     }
 }