To make `CodeLocation` reusable across different components, require
that a commit's `Oid` is part of the struct.
An `Oid` is necessary since the `path` can refer to a path at any
point in time throughout the history of the repository. By pinning the
commit that is being referred to, the path will refer to the path
within the associated tree [of the commit].
Signed-off-by: Fintan Halpenny <fintan.halpenny@gmail.com>
X-Clacks-Overhead: GNU Terry Pratchett