Some refactoring to help address bug #531967.
* bzrlib/tests/test_conflicts.py:
(TestParametrizedResolveConflicts.check_resolved): Use 'path' as
the parameter name as it's clearer than 'item'.
* bzrlib/conflicts.py:
(PathConflict._resolve): Implement the rename with a proper
TreeTransform. This doesn't address bug #531967 yet.
(PathConflict._get_or_infer_file_id): First (unsuccesful) try to
infer the file-id.
(ContentsConflict._resolve): Renamed from _take_it.