Java: avoid provider resource extraction when library already exists in onnxruntime.native.path (microsoft#27668)

## Summary

Fixes the Java native provider loading flow so that
`extractProviderLibrary` checks
`onnxruntime.native.path` before attempting extraction from classpath
resources.

Previously, when a provider library was already present in
`onnxruntime.native.path`,
the Java loader could still attempt `extractFromResources(...)` first,
and only fall
back to the configured native path afterwards. This caused an
unnecessary extraction
attempt even though the library was already available on disk.

This change updates the lookup order to:

1. Return immediately if the provider was already marked as ready
2. Check whether the provider library already exists in
`onnxruntime.native.path`
3. Only if not found there, attempt extraction from classpath resources

## Tests

Added a regression test covering the case where the requested provider
library already
exists in `onnxruntime.native.path`.

The test verifies that:

- `extractProviderLibrary(...)` returns `true`
- extraction from resources is not attempted in that case

A small test-only hook was added to observe calls to
`extractFromResources(...)` so the
regression can be validated directly and deterministically.

## Issue

Fixes microsoft#27655

Author: TsofnatMaman

java/src/main/java/ai/onnxruntime/OnnxRuntime.java

@@ -307,26 +307,22 @@ static synchronized boolean extractProviderLibrary(String libraryName) {
     if (extractedSharedProviders.contains(libraryName)) {
       return true;
     }
-    // Otherwise extract the file from the classpath resources
+    // If a native library directory is configured, prefer it and skip extraction when present.
+    if (libraryDirPathProperty != null) {
+      String libraryFileName = mapLibraryName(libraryName);
+      File libraryFile = Paths.get(libraryDirPathProperty, libraryFileName).toFile();
+      if (libraryFile.exists()) {
+        extractedSharedProviders.add(libraryName);
+        return true;
+      }
+    }
+    // Otherwise extract the file from the classpath resources.
     Optional<File> file = extractFromResources(libraryName);
     if (file.isPresent()) {
       extractedSharedProviders.add(libraryName);
       return true;
     } else {
-      // If we failed to extract it, check if there is a valid cache directory
-      // that contains it
-      if (libraryDirPathProperty != null) {
-        String libraryFileName = mapLibraryName(libraryName);
-        File libraryFile = Paths.get(libraryDirPathProperty, libraryFileName).toFile();
-        if (libraryFile.exists()) {
-          extractedSharedProviders.add(libraryName);
-          return true;
-        } else {
-          return false;
-        }
-      } else {
-        return false;
-      }
+      return false;
     }
   }