[core] Massive setting system update

- Get rid of attribute crap. Now only interface is required
- Rename canUse to isAdmin in `Bot.IsUserAdminAsync` to match the actual meaning of variable
- Made `AnswerQuery` reusable by moving it from ContentStore to Core's CommonHandler
- Chat Settings edit frontend (inline keyboard)
- Rename NsfwOption to AllowNsfw and move it to ContentStore module
- Remove option backend testing commands
- Add KarmaMode option as an example of Select option type

Core/Extensions/BotExtension.cs

@@ -22,14 +22,14 @@ namespace Kruzya.TelegramBot.Core.Extensions
         public static async Task<bool> IsUserAdminAsync(this ITelegramBotClient bot, Chat chat, User user)
         {
             var callerMember = await bot.GetChatMemberAsync(chat, user.Id);
-            var canUse = callerMember is ChatMemberOwner;
+            var isAdmin = callerMember is ChatMemberOwner;
 
             if (callerMember is ChatMemberAdministrator callerAdmin)
             {
-                canUse = callerAdmin.CanRestrictMembers;
+                isAdmin = callerAdmin.CanRestrictMembers;
             }
 
-            return canUse;
+            return isAdmin;
         }
 
         public static async Task<bool> CanDeleteMessagesAsync(this ITelegramBotClient bot, Chat chat)