Add PEM to DER conversion support in WolfCrypt class

[cconlon]

This PR wraps native wolfSSL APIs wc_KeyPemToDer(), wc_CertPemToDer(), and wc_PubKeyPemToDer() in the com.wolfssl.WolfCrypt class:

public static byte[] keyPemToDer(byte[] pem, String password);
public static byte[] certPemToDer(byte[] pem);
public static byte[] pubKeyPemToDer(byte[] pem);

JUnit tests are added as part of this PR.

[Copilot]

Pull request overview

This PR adds PEM to DER conversion functionality to the WolfCrypt Java bindings by wrapping native wolfSSL APIs (wc_KeyPemToDer(), wc_CertPemToDer(), and wc_PubKeyPemToDer()) in the com.wolfssl.WolfCrypt class.

Key Changes

• Three new public static methods in WolfCrypt.java for PEM to DER conversions (private keys, certificates, public keys)
• JNI C implementation with proper memory management and error handling
• Comprehensive JUnit test suite with 22 test cases covering normal operations, edge cases, and threading scenarios

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/main/java/com/wolfssl/wolfcrypt/WolfCrypt.java	Adds three public static methods (keyPemToDer, certPemToDer, pubKeyPemToDer) with input validation and documentation
jni/jni_wolfcrypt.c	Implements JNI native functions with proper memory management, error handling, and conditional compilation
jni/include/com_wolfssl_wolfcrypt_WolfCrypt.h	Adds JNI function declarations for the three new native methods
src/test/java/com/wolfssl/wolfcrypt/test/WolfCryptTest.java	Comprehensive test suite with 585 lines covering functionality, error cases, and thread safety
src/test/java/com/wolfssl/wolfcrypt/test/WolfCryptTestSuite.java	Adds WolfCryptTest.class to the test suite

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 5 comments.

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