rust-dirstate-entry: add `modified` method This will also be used in other places later in the series. Differential Revision: https://phab.mercurial-scm.org/D12536

rust: remove use of `EntryState` in `DirsMultiset` Let's use the new API. Differential Revision: https://phab.mercurial-scm.org/D12535

rust: use `entry.tracked()` directly This is the new API Differential Revision: https://phab.mercurial-scm.org/D12534

rust-hg-cpython: remove use of `EntryState` Let's use the new API Differential Revision: https://phab.mercurial-scm.org/D12533

rust-dirstatemap: use a checked sub instead of a potentially underflowing one This was missed in 2593873cda0f Differential Revision: https://phab.mercurial-scm.org/D12532

rust-dirstatemap: add simpler version of `get_node_mut` This will help reduce code and footgun potential for simpler callers. Differential Revision: https://phab.mercurial-scm.org/D12531

rust-dirstatemap: use `get_node_mut` instead or `get_or_insert_node` This (along with the docstring), makes it more obvious that we're not expecting to insert a node here. This is less prone to bugs in later refactorings. Differential Revision: https://phab.mercurial-scm.org/D12530

rust-dirstatemap: add `each_ancestor` argument to `get_node_mut` This forces the callers to think about if the counters in the ancestors need to be adjusted. Differential Revision: https://phab.mercurial-scm.org/D12529