Record build details of rust snaps

We have already implemented recording for python and nodejs snaps.

This topic is to start the discussion and implementation of the details to record from rust snaps.

Rust is pretty nice, because it’s new and follows newer standards. After the snap is build, a Cargo.lock file will be left in the build directory. This file contains the names and versions of all the cargo packages installed during the build.

This pr records it:

And this is how the manifest.yaml file will look like:

cc @tyhicks @ratliff

In addition to that, I think it would be good to record the versions of rustup, rustc and cargo. They are all installed by the rustup script that is downloaded by the plugin.