Added the `parse_refname` function for parsing a reference into its
`TypeName` and `ObjectId`, if possible.
This replaces the `cob_suffix` function in `radicle`.
This change also fixes the `FromStr` instance of `ObjectId` to use
`from_str` instead of `TryFrom` for bytes.
Signed-off-by: Fintan Halpenny <fintan.halpenny@gmail.com>
X-Clacks-Overhead: GNU Terry Pratchett