Remove the UserDir discovery provider in favour of new AppDir provider

The intention for the user dir provider was always to return the
same directory that the application was installed in - in almost
all cases this would be expected to be the "current" directory as
obtained from the user.dir system property.

However, the current directory is not necessarily the same as the
installation directory.

So instead, remove that provider and replace it with one that uses
class loader protection domain and code source to find the file
location containing the vlcj class files and return this as the
application directory.

Author: caprica

src/main/java/module-info.java

@@ -74,13 +74,13 @@
 
     // Standard implementations of native library discovery directory providers
     provides uk.co.caprica.vlcj.factory.discovery.provider.DiscoveryDirectoryProvider with
+        uk.co.caprica.vlcj.factory.discovery.provider.AppDirDirectoryProvider,
         uk.co.caprica.vlcj.factory.discovery.provider.ConfigDirConfigFileDiscoveryDirectoryProvider,
         uk.co.caprica.vlcj.factory.discovery.provider.JnaLibraryPathDirectoryProvider,
         uk.co.caprica.vlcj.factory.discovery.provider.LinuxWellKnownDirectoryProvider,
         uk.co.caprica.vlcj.factory.discovery.provider.MacOsWellKnownDirectoryProvider,
         uk.co.caprica.vlcj.factory.discovery.provider.SystemPathDirectoryProvider,
         uk.co.caprica.vlcj.factory.discovery.provider.UserDirConfigFileDiscoveryDirectoryProvider,
-        uk.co.caprica.vlcj.factory.discovery.provider.UserDirDirectoryProvider,
         uk.co.caprica.vlcj.factory.discovery.provider.WindowsInstallDirectoryProvider;
 
     // Standard implementations of native library discovery strategy providers

src/main/java/uk/co/caprica/vlcj/factory/discovery/provider/AppDirDirectoryProvider.java

@@ -0,0 +1,63 @@
+/*
+ * This file is part of VLCJ.
+ *
+ * VLCJ 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.
+ *
+ * VLCJ 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 VLCJ.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Copyright 2009-2025 Caprica Software Limited.
+ */
+
+package uk.co.caprica.vlcj.factory.discovery.provider;
+
+import java.io.File;
+import java.net.URL;
+import java.security.CodeSource;
+import java.security.ProtectionDomain;
+
+/**
+ * Implementation of a directory provider that returns the directory the application is installed in.
+ */
+public class AppDirDirectoryProvider implements DiscoveryDirectoryProvider {
+
+    @Override
+    public int priority() {
+        return DiscoveryProviderPriority.APP_DIR;
+    }
+
+    @Override
+    public String[] directories() {
+        try {
+            Class<?> clazz = DiscoveryDirectoryProvider.class;
+            ProtectionDomain protectionDomain = clazz.getProtectionDomain();
+            CodeSource codeSource = protectionDomain.getCodeSource();
+            if (codeSource != null) {
+                URL location = codeSource.getLocation();
+                if (location != null) {
+                    File file = new File(location.toURI());
+                    if (!file.isDirectory()) {
+                        file = file.getParentFile();
+                    }
+                    return new String[] { file.getAbsolutePath() };
+                }
+            }
+            return new String[0];
+        } catch (Exception e) {
+            return new String[0];
+        }
+    }
+
+    @Override
+    public boolean supported() {
+        return true;
+    }
+}

src/main/java/uk/co/caprica/vlcj/factory/discovery/provider/DiscoveryProviderPriority.java

@@ -28,7 +28,7 @@ public interface DiscoveryProviderPriority {
 
     int JNA_LIBRARY_PATH = -1;
 
-    int USER_DIR = -2;
+    int APP_DIR = -2;
 
     int INSTALL_DIR = -3;