treat banned plugins like out of date, dont load but allow update

Dalamud/Plugin/Internal/Exceptions/BannedPluginException.cs

@@ -0,0 +1,22 @@
+namespace Dalamud.Plugin.Internal.Exceptions
+{
+    /// <summary>
+    /// This represents a banned plugin that attempted an operation.
+    /// </summary>
+    internal class BannedPluginException : PluginException
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="BannedPluginException"/> class.
+        /// </summary>
+        /// <param name="message">The message describing the invalid operation.</param>
+        public BannedPluginException(string message)
+        {
+            this.Message = message;
+        }
+
+        /// <summary>
+        /// Gets the message describing the invalid operation.
+        /// </summary>
+        public override string Message { get; }
+    }
+}