Add Java 9+ module support (JPMS) for jlink compatibility

[cconlon]

This PR adds Java 9+ module support (JPMS) to wolfSSL JNI/JSSE, enabling use with jlink for creating custom Java runtimes. We maintain full backward compatibility with Java 8, since module-info.java is conditionally compiled in based on Java version.

New Files:

• src/java9/module-info.java - Module descriptor declaring com.wolfssl module
• .github/workflows/java-module-test.yml - CI workflow validating module support

Modified Files:

• build.xml - Added conditional compilation of module-info (Java 9+ only)
• pom.xml - Added Maven profile for module-info compilation on Java 9+
• README.md - Added documentation for module support and jlink usage

Both Ant and Maven use conditional compilation based on JDK version:

JDK Used to Build	Resulting JAR
Java 8	Standard JAR (no module-info.class)
Java 9+	Modular JAR (includes module-info.class)

The module descriptor:

• Declares module as com.wolfssl
• Exports com.wolfssl and com.wolfssl.provider.jsse packages
• Declares uses java.security.Provider for ServiceLoader compatibility
• Registers WolfSSLProvider as a java.security.Provider service

Addresses issue: #85

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