Remove deprecated File-based extractResources() method

After successfully migrating all 704 integration tests to use the new
Path-based extractResourcesAsPath() method, the old File-based method
is no longer needed and has been removed.

Changes:
- Removed extractResources() method from AbstractMavenIntegrationTestCase
- Updated tests to verify Path-to-File conversion instead of backward compatibility
- All integration tests compile successfully without the deprecated method
- All unit tests pass

This completes the full migration to NIO2 Path API for integration tests.
The codebase now exclusively uses modern Path-based operations, providing
better performance, improved cross-platform compatibility, and cleaner code.

Author: gnodet

its/core-it-support/maven-it-helper/src/main/java/org/apache/maven/it/AbstractMavenIntegrationTestCase.java

@@ -73,10 +73,6 @@ public void close() throws IOException {}
 
 
 
-    protected File extractResources(String resourcePath) throws IOException {
-        return extractResourcesAsPath(resourcePath).toFile();
-    }
-
     /**
      * Extracts test resources to a temporary directory.
      *

its/core-it-support/maven-it-helper/src/test/java/org/apache/maven/it/AbstractMavenIntegrationTestCaseNIO2Test.java

@@ -44,18 +44,18 @@ void testExtractResourcesAsPath() throws IOException {
     }
 
     @Test
-    void testExtractResourcesBackwardCompatibility() throws IOException {
+    void testPathToFileConversion() throws IOException {
         String resourcePath = "test-resource";
-        
-        // Test that the old File-based method still works
-        File result = extractResources(resourcePath);
-        
-        assertNotNull(result);
-        assertTrue(result.isAbsolute());
-        assertTrue(result.getPath().endsWith(resourcePath));
-        
-        // Verify that both methods return equivalent paths
+
+        // Test that Path can be converted to File when needed
         Path pathResult = extractResourcesAsPath(resourcePath);
-        assertEquals(pathResult.toFile(), result);
+        File fileResult = pathResult.toFile();
+
+        assertNotNull(fileResult);
+        assertTrue(fileResult.isAbsolute());
+        assertTrue(fileResult.getPath().endsWith(resourcePath));
+
+        // Verify round-trip conversion
+        assertEquals(pathResult, fileResult.toPath());
     }
 }

its/core-it-support/maven-it-helper/src/test/java/org/apache/maven/it/NIO2MigrationVerificationTest.java

@@ -76,17 +76,17 @@ void testPathToStringPattern() throws IOException {
     }
 
     @Test
-    void testBackwardCompatibilityWithFileAPI() throws IOException {
-        // Verify that the old File-based method still works
-        java.io.File testDir = extractResources("test-resource");
-        
-        assertNotNull(testDir);
-        assertTrue(testDir.isAbsolute());
-        assertTrue(testDir.getPath().endsWith("test-resource"));
-        
-        // Verify both methods return equivalent paths
-        Path pathResult = extractResourcesAsPath("test-resource");
-        assertEquals(pathResult.toFile(), testDir);
+    void testPathToFileConversion() throws IOException {
+        // Verify that Path can be converted to File when needed for legacy APIs
+        Path testDir = extractResourcesAsPath("test-resource");
+        java.io.File fileDir = testDir.toFile();
+
+        assertNotNull(fileDir);
+        assertTrue(fileDir.isAbsolute());
+        assertTrue(fileDir.getPath().endsWith("test-resource"));
+
+        // Verify round-trip conversion
+        assertEquals(testDir, fileDir.toPath());
     }
 
     @Test