Fuzzing via honggfuzz (#101)

* feat: Added Fuzzing via honggfuzz

* feat: Extended fuzzing harness, more crashes

* fix: Review changes, thanks @tirr-c

* fix: Removed comments used for testing

* fix: Mistake introduced by IDE refactoring, unnecessary drop removed

* fix: Possible integer overflow in compute_default_width

* fix: mistake with the fix

* fix: honggfuzz does not support windows yet, so disabled fuzzing there for now

* doc: Added Readme, testing: Preparing for tests in jxl-oxide

* refactor: moved tests to own directory, added to .gitignore, committed Cargo.lock

* doc: Improved Fuzzing Readme

* doc: Added note about core counts to Fuzzing Readme

* fix: max size not needed for tests

* fix: Removed extra Cargo.lock

* Removed unnecessary lines from jxl-oxide-fuzz/.gitignore

Co-authored-by: Wonwoo Choi <chwo9843@gmail.com>

* Formatting jxl-oxide-fuzz/Cargo.toml

Co-authored-by: Wonwoo Choi <chwo9843@gmail.com>

* refactor: Removed unnecessary line from test_fuzz_findings, removed left over files

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Co-authored-by: Wonwoo Choi <chwo9843@gmail.com>