Fix AES-GCM edge cases to allow for null input or output arrays

[cconlon]

This PR fixes both JNI and JCE levels for AES-GCM usage to allow for the cases where a user may pass in a null input/plaintext, or provide a null output buffer. These are scenarios where a user may provide Additional Authenticated Data during encrypt() to generate an auth tag.

JUnit test cases have been added for regression prevention.

This fixes the OpenJDK SunJCE test: crypto/provider/Cipher/AES/TestKATForGCM.java

[Copilot]

Pull Request Overview

This PR fixes AES-GCM edge cases to handle null input/output arrays for scenarios where users only provide Additional Authenticated Data (AAD) to generate authentication tags. The changes ensure compatibility with OpenJDK SunJCE test requirements.

Key changes:

• Modified JNI validation logic to allow null plaintext/ciphertext when only generating authentication tags
• Updated JCE cipher implementation to handle null input arrays correctly during encryption/decryption
• Added comprehensive test cases for null plaintext scenarios with and without AAD

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
jni/jni_aesgcm.c	Updated input validation to allow null input arrays for GMAC operations
src/main/java/com/wolfssl/provider/jce/WolfCryptCipher.java	Added null-safety check before array copy operations
src/test/java/com/wolfssl/wolfcrypt/test/AesGcmTest.java	Updated existing tests and added new test cases for null plaintext scenarios
src/test/java/com/wolfssl/provider/jce/test/WolfCryptCipherTest.java	Added JCE-level test cases for null plaintext with OpenJDK test vectors

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[rlm2002]

Looks good. The branch conflicts just need to be resolved.