rust: move code from utils to utils::strings
This moves string-related functions in hg::utils into the recently added
hg::utils::strings module.
use std::path::Path;
/// The Mercurial transaction system is based on the append-only nature
/// of its core files. This exposes the necessary methods to safely write to
/// the different core datastructures.
pub trait Transaction {
/// Record the state of an append-only file before update
fn add(&mut self, file: impl AsRef<Path>, offset: usize);
// TODO the rest of the methods once we do more in Rust.
}