Ban message improvements (#14731)

Server config now provide appeals forum link, game admins won't need to type it out manually anymore.
Add warning about trying to ban evade.
Cleaned up code a bit.

Content.Shared/CCVar/CCVars.cs

@@ -1475,6 +1475,12 @@ namespace Content.Shared.CCVar
         public static readonly CVarDef<string> InfoLinksBugReport =
             CVarDef.Create("infolinks.bug_report", "", CVar.SERVER | CVar.REPLICATED);
 
+        /// <summary>
+        /// Link to site handling ban appeals. Shown in ban disconnect messages.
+        /// </summary>
+        public static readonly CVarDef<string> InfoLinksAppeal =
+            CVarDef.Create("infolinks.appeal", "", CVar.SERVER | CVar.REPLICATED);
+
         /*
          * CONFIG
          */