init: use `get_clone_path` when suitable
`hg init` has this weird feature were you can refer to `[paths]` entry select the path to initialize. We move that code to the new APIs.
Differential Revision: https://phab.mercurial-scm.org/D10418
To run the tests, do:
cd tests/
python run-tests.py
See https://mercurial-scm.org/wiki/WritingTests for
more information on writing tests.