rust-dirstate: use a struct as arguments for the high-level `reset_state` This makes the interface a lot clearer at the call site and prevents silly mistakes, as an API with a bunch of booleans is prone to errors. This refactor adds a `from_empty` parameter for a fast-path when resetting and entry we're sure does not exist. It will be used in the upcoming update Rust fastpath, and was not split to prevent more churn.