Native Libraries: added API version to:

- test whether native library matches the JAR (bad builds could e.g. ship a newer JAR with an older incompatible native library)
- invoke a method (to get API version) to check whether native library works correctly

if API version do not match, or method could not invoked correctly, disable usage of FlatLaf native library

Windows and macOS binaries built and signed locally in clean workspace
Linux binary built by GitHub Actions

flatlaf-natives/flatlaf-natives-windows/src/main/headers/com_formdev_flatlaf_ui_FlatNativeLibrary.h

@@ -0,0 +1,21 @@
+/* DO NOT EDIT THIS FILE - it is machine generated */
+#include <jni.h>
+/* Header for class com_formdev_flatlaf_ui_FlatNativeLibrary */
+
+#ifndef _Included_com_formdev_flatlaf_ui_FlatNativeLibrary
+#define _Included_com_formdev_flatlaf_ui_FlatNativeLibrary
+#ifdef __cplusplus
+extern "C" {
+#endif
+/*
+ * Class:     com_formdev_flatlaf_ui_FlatNativeLibrary
+ * Method:    getApiVersion
+ * Signature: ()I
+ */
+JNIEXPORT jint JNICALL Java_com_formdev_flatlaf_ui_FlatNativeLibrary_getApiVersion
+  (JNIEnv *, jclass);
+
+#ifdef __cplusplus
+}
+#endif
+#endif