Summary: Ref T4327. Moves us one small step forward toward testable change parsers by separating out this unrelated logic from the PullLocal daemon. We will also probably want to run this logic so we can do remote path lookups to limit the role of Arcanist Projects in the future, which is why I made the URI type (here, only "git") a parameter rather than calling this a `GitURINormalizer` or something.
Test Plan:
- Ran unit tests.
- Ran `repository discover` on a correctly-configured remote repository.
- Ran `repository discover` on an incorrectly-configured remote, got an error message.
Reviewers: btrahan
Reviewed By: btrahan
CC: aran
Maniphest Tasks: T4327
Differential Revision: https://secure.phabricator.com/D7981
