Support non-Rust binaries for Ziggy's binary mode fuzzing

[kevin-valerio]

Ziggy fuzzing's mode currently support binary mode with -b to fuzz binary instrumented with AFL compilers. However, if the current directory doesn't contain a proper Rust Cargo.toml, the fuzzing campaign won't start:

> cargo ziggy fuzz -b harness --dict func.dict -j 5 --asan -t 5 -C binary -c corpora/
    Launched afl

See more live information by running:
  tail -f ./output/harness/logs/afl.log
  tail -f ./output/harness/logs/afl_1.log
Error: Failure running fuzzers

Caused by:
    `cargo metadata` exited with an error: error: could not find `Cargo.toml` in `/../example/cpp/build` or any parent directory

[R9295]

Would this be something you are capable of contributing @kevin-valerio ?