dirstate-tree: Add a dirstate-v1-tree variant of some tests
The `dirstate-v1` variant has the previous behavior.
`dirstate-v1-tree` uses the same format on disk, but uses the new
`DirstateMap` with a tree data structure and the new `status` algorithm.
These were untested so far.
Differential Revision: https://phab.mercurial-scm.org/D10698
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