use camino #308
Description
We don't have any use-case that requires support for non-UTF8 characters in file paths but we're using Path & PathBuf which require effectively ignoring / dropping non-UTF8 characters. So our impl will fail to work on systems that have non-UTF8 characters in file system paths despite us doing this extra work. We're probably better off using camino and explicitly disallowing non-UTF8 file paths completely. This larger task is derived from #306 that replaced our use of the std types w/ camino in the attest-mock cli while also refactoring attest-mock to provide a library / API.