Plugins: Add ICorePlugin, enable by default

Il2CppInspector.Common/Plugins/Internal/ICorePlugin.cs

@@ -0,0 +1,14 @@
+/*
+    Copyright 2021 Katy Coe - http://www.djkaty.com - https://github.com/djkaty
+
+    All rights reserved.
+*/
+
+namespace Il2CppInspector.PluginAPI.V100
+{
+    /// <summary>
+    /// Interface denoting a plugin that is an internal part of Il2CppInspector
+    /// For internal use only
+    /// </summary>
+    public interface ICorePlugin : IPlugin { }
+}

Il2CppInspector.Common/Plugins/Internal/PluginManager.cs

@@ -214,7 +214,10 @@ namespace Il2CppInspector
                             if (AsInstance.ManagedPlugins.Any(p => p.Plugin.Id == plugin.Id))
                                 throw new Exception($"Multiple copies of {plugin.Name} were found. Please ensure the plugins folder only contains one copy of each plugin.");
 
-                            AsInstance.ManagedPlugins.Add(new ManagedPlugin { Plugin = plugin, Available = true, Enabled = false });
+                            // Enable internal plugins by default
+                            var enabled = typeof(ICorePlugin).IsAssignableFrom(type);
+
+                            AsInstance.ManagedPlugins.Add(new ManagedPlugin { Plugin = plugin, Available = true, Enabled = enabled });
                         }
 
                         // Add older versions here with adapters