Creates a git_annotated_commit from the given commit id. The resulting git_annotated_commit must be freed with git_annotated_commit_free.

An annotated commit contains information about how it was looked up, which may be useful for functions like merge or rebase to provide context to the operation. For example, conflict files will include the name of the source or target branches being merged. It is therefore preferable to use the most specific function (eg git_annotated_commit_from_ref) instead of this one when that data is known.