Decouple some plugins from QuickLook

QuickLook.Plugin/QuickLook.Plugin.PluginInstaller/App.cs

@@ -0,0 +1,53 @@
+// Copyright © 2024 QL-Win Contributors
+//
+// This file is part of QuickLook program.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+using QuickLook.Common.Helpers;
+using System;
+using System.IO;
+using System.Linq;
+using System.Reflection;
+
+namespace QuickLook.Plugin.PluginInstaller;
+
+internal static class App
+{
+    /// <summary>
+    /// <see cref="QuickLook.App.UserPluginPath"/>
+    /// </summary>
+    public static string UserPluginPath
+    {
+        get
+        {
+            // Just in case
+            static string Fallback() => Path.Combine(SettingHelper.LocalDataPath, "QuickLook.Plugin\\");
+
+            try
+            {
+                var loadedAssemblies = AppDomain.CurrentDomain.GetAssemblies()
+                    .First(a => a.GetName(false).Name == "QuickLook");
+                var appType = loadedAssemblies?.GetType("QuickLook.App");
+                var fieldInfo = appType?.GetField(nameof(UserPluginPath), BindingFlags.Public | BindingFlags.Static);
+
+                return (fieldInfo?.GetValue(null) as string) ?? Fallback();
+            }
+            catch
+            {
+                return Fallback();
+            }
+        }
+    }
+}