Add SHA-384 and SHA-512 support with OpenSSL hash functions and tests

[Copilot]

• Add SHA-384 and SHA-512 OpenSSL hash functions to merklecpp.h
• Add type aliases (Tree384, Tree512, etc.) to merklecpp.h
• Add templated make_hashesT utility in test/util.h
• Add SHA-384 and SHA-512 unit tests in test/unit_tests.cpp
• Extend test/compare_hash_functions.cpp with SHA-384/SHA-512 benchmarks
• Extend test/time_large_trees.cpp with SHA-384/SHA-512 large tree timing
• Build and run all 12 tests successfully
• Remove codeql build artifacts and add to .gitignore

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[achamayou]

@copilot good start, but please also extend the tests in:

• compare_hash_functions.cpp
• time_large_trees.cpp

[Copilot]

@copilot good start, but please also extend the tests in:

• compare_hash_functions.cpp
  ...

Extended both tests in dfadccb:

• compare_hash_functions.cpp: Added a generic benchT template and SHA-384/SHA-512 benchmark calls under HAVE_OPENSSL
• time_large_trees.cpp: Added SHA-384 and SHA-512 large tree timing blocks (same leaf count/root interval as SHA-256)

All 12 tests pass.

[achamayou]

@copilot ok none of the stuff under _codeql_build_dir should be checked in, can you please:

1. remove them all, add the relevant to gitignore if you must
2. explain why these files are created in the first place

[Copilot]

@copilot ok none of the stuff under _codeql_build_dir should be checked in, can you please:

1. remove them all, add the relevant to gitignore if you must
   ...

Removed all _codeql_build_dir/ and _codeql_detected_source_root files from tracking and added both to .gitignore in 0576188.

These files were created by the CodeQL security scanner tool that I ran as part of my workflow to check for vulnerabilities in the code changes. The tool runs a CMake build in a _codeql_build_dir/ directory and writes a _codeql_detected_source_root symlink. These are ephemeral build artifacts that should not be checked in — they were accidentally picked up by git add . during a progress commit.