## Summary
This PR does the following:
1. Remove the symlinks from the `fuzz/` directory
2. Update `init-fuzzer.sh` script to create those symlinks
3. Update `fuzz/.gitignore` to ignore those corpus directories
## Test Plan
Initialize the fuzzer:
```sh
./fuzz/init-fuzzer.sh
```
And, run a fuzz target:
```sh
cargo +nightly fuzz run ruff_parse_simple -- -timeout=1 -only_ascii=1
```
Improves the `ruff_parse_simple` fuzz harness by adding checks for
parsed locations to ensure they all lie on UTF-8 character boundaries.
This will allow for faster identification of issues like #5004.
This also adds additional details for Apple M1 users and clarifies the
importance of using `init-fuzzer.sh` (thanks for the feedback,
@jasikpark 🙂).