debugstate: Always call dirstatemap.debug_iter()
… passing it a new `all` argument for the `--all` CLI option,
instead of conditionally calling `.debug_iter()` or `.items()`
This prepares for the next commit.
Differential Revision: https://phab.mercurial-scm.org/D11462
rust: Make the fields of DirstateEntry private
This is a first step toward making its internal structure equivalent to
Python’s DirstateItem.
Differential Revision: https://phab.mercurial-scm.org/D11461