When grummage launches, it should check for the grype binary in the $PATH and the current directory.

If the grype binary is not found, we should display an error and stop execution as a minimum effort.

In the best-case scenario, let's offer to download grype using the official installation instructions (curl piped to bash) to the current directory.

In a future release, we could have an environment variable that points to the grype binary rather than having to hunt for it. I am open to discussion about this one.