feat: Expand fuzz testing suite and enhance diagnostics

[JacobBorden]

This commit significantly expands the fuzz testing capabilities of the project.

Key changes include:

• Added UndefinedBehaviorSanitizer (UBSan) to the fuzzing configuration alongside AddressSanitizer (ASan) for more comprehensive bug detection.
• Introduced four new fuzz targets:
  • fuzz_bmp_tool_save: Targets the BmpTool::save functionality.
  • fuzz_bitmap_file: Targets Bitmap::File class operations.
  • fuzz_image_operations: Targets various image manipulation functions.
  • fuzz_matrix: Targets Matrix class operations.
• Updated the existing fuzz_bitmap target to use the new sanitizer configuration.
• Modified the CMake build system (tests/CMakeLists.txt) to correctly build all five fuzz targets when ENABLE_FUZZING is ON.
• Enhanced the GitHub Actions fuzzing workflow (.github/workflows/fuzzing.yml):
  • Builds all available fuzz targets.
  • Runs each of the five fuzzers independently.
  • Creates separate corpus directories for each fuzzer.
  • Added -print_pcs=1 libFuzzer option for better call stack information on new coverage.
• Updated README.md with a new "Fuzz Testing" section, detailing the available targets and how to enable/run them.

These changes aim to improve code robustness by systematically testing more parts of the codebase against a wider range of inputs and conditions.