enable neo core to remove the assembly file if user delete a plugin.

src/neo/Plugins/Plugin.cs

@@ -29,6 +29,11 @@ public abstract class Plugin : IDisposable
         /// </summary>
         public static readonly List<Plugin> Plugins = new();
 
+        /// <summary>
+        /// Assemblies of plugin files
+        /// </summary>
+        public static readonly Dictionary<string, (Assembly, int)> Assemblies = new();
+
         internal static readonly List<ILogPlugin> Loggers = new();
         internal static readonly Dictionary<string, IStorageProvider> Storages = new();
         internal static readonly List<IPersistencePlugin> PersistencePlugins = new();
@@ -197,19 +202,27 @@ private static void LoadPlugin(Assembly assembly)
         internal static void LoadPlugins()
         {
             if (!Directory.Exists(PluginsDirectory)) return;
-            List<Assembly> assemblies = new();
             foreach (string rootPath in Directory.GetDirectories(PluginsDirectory))
             {
                 foreach (var filename in Directory.EnumerateFiles(rootPath, "*.dll", SearchOption.TopDirectoryOnly))
                 {
                     try
                     {
-                        assemblies.Add(Assembly.Load(File.ReadAllBytes(filename)));
+                        if (Assemblies.ContainsKey(filename))
+                        {
+                            Assemblies[filename] = (Assemblies[filename].Item1, Assemblies[filename].Item2 + 1);
+                        }
+                        else
+                        {
+                            var assembly = Assembly.Load(File.ReadAllBytes(filename));
+                            Assemblies.Add(filename, (assembly, 1));
+                            LoadPlugin(assembly);
+                        }
                     }
                     catch { }
                 }
             }
-            foreach (Assembly assembly in assemblies)
+            foreach (var (_, (assembly, _)) in Assemblies)
             {
                 LoadPlugin(assembly);
             }