This commit addresses the issue of recursion in the TryFrom
call of Reference by resolving the parent in a lazy way.
Due to constraints posed by the need to access `git2::Repository`
or `git2::Commit` to resolve the parent, this commit decides to
pull out the parent resolution logic from the `cob::object::Commit`
module and move it inside the `cob::store::Store` implementation by adding
a new method `parents_of`.
Suggested-by: Fintan Halpenny <fintan.halpenny@gmail.com>
Tested-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Signed-off-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
b29321dbf7