[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/Options/CodeWatcherMode.cs

@@ -0,0 +1,21 @@
+using Kruzya.TelegramBot.Core.Options;
+
+namespace West.TelegramBot.CodeWatcher.Options;
+
+public class CodeWatcherMode : AbstractOption<CodeWatcherMode, string>
+{
+    public override string OptionId => "codeWatcherMode";
+    public override string OptionName => "CodeWatcher™ mode";
+    public override OptionType OptionType => OptionType.Select;
+    public override string DefaultValue => "remove";
+
+    public CodeWatcherMode(IOptionProvider optionProvider) : base(optionProvider)
+    {
+        ChoiceList.AddRange(new []
+        {
+            new SelectChoice("disabled", "Disabled", "D"),
+            new SelectChoice("remove", "Remove", "R"),
+            new SelectChoice("upload", "Upload", "U")
+        });
+    }
+}