dirstate-entry: introduce dedicated accessors for v1 serialization In the spirit of changing the content and storage of the dirstate entry, we add new method that the code doing v1 serialisation can use. Adding such method to the C object is quite trivial. Differential Revision: https://phab.mercurial-scm.org/D10951

dirstate-entry: goes through the `dirstatetuple` constructor in all cases We need to make sure we build an object. Differential Revision: https://phab.mercurial-scm.org/D10950

dirstate-entry: turn dirstate tuple into a real object (like in C) With dirstate V2, the stored information and actual format will change. This mean we need to start an a better abstraction for a dirstate entry that a tuple directly accessed. By chance, the C code is already doing this and pretend to be a tuple. So it should be fairly easy. We start with turning the tuple into an object, we will slowly migrate the dirstate code to no longer use the tuple directly in later changesets. Differential Revision: https://phab.mercurial-scm.org/D10949