[Feature] add build/test dependencies to rocks.lock

[mrcjkb]

The project lockfile should probably include build/test dependencies.
This makes me think we might want to introduce a type like:

struct RocksLock<P: LockfilePermissions> {
  tree: DepsLock,
  test_tree: Option<DepsLock>,
  build_tree: Option<DepsLock>,
}

where DepsLock is equivalent to the current Lockfile struct, but without the filepath fields.