dirstate-item: implement `v1_mtime` with higher level block This is much easier to read and maintain. Differential Revision: https://phab.mercurial-scm.org/D11375

dirstate-item: implement `v1_size` with higher level block This is much easier to read and maintain. Differential Revision: https://phab.mercurial-scm.org/D11374

dirstate-item: implement v1_state with higher level block This is much easier to read and maintain. Differential Revision: https://phab.mercurial-scm.org/D11373

dirstate-item: add more logic to `from_p2` This seem semantically better even if this tracking case seems to always comes with clean_p2 for now. Differential Revision: https://phab.mercurial-scm.org/D11372

dirstate-item: implement `merged_removed` in a simpler way We can simply use the underlying attribute. Differential Revision: https://phab.mercurial-scm.org/D11371

dirstate-item: implement `removed` in a simpler way We can simply use the underlying attribute. Differential Revision: https://phab.mercurial-scm.org/D11370

dirstate-item: implement `from_p2_removed` in a simpler way We can simply use the underlying attribute. Differential Revision: https://phab.mercurial-scm.org/D11369

dirstate-item: implement `from_p2` in a simpler way We can simply use the underlying attribute. Differential Revision: https://phab.mercurial-scm.org/D11368

dirstate-item: implement `merged` in a simpler way We can simply use the underlying attribute. Differential Revision: https://phab.mercurial-scm.org/D11367

dirstate-item: implement `added` in a simpler way We can simply use the underlying attribute. Differential Revision: https://phab.mercurial-scm.org/D11366

dirstate-item: implement `tracked` in a simpler way We can simply use the underlying attribute. Differential Revision: https://phab.mercurial-scm.org/D11365

dirstate-item: keep the full information in memory (for pure form) This changeset is finally reaching the area where we have been headed this whole time. Since all implementation details are contained inside de DirstateItem logic, we can change the way it is implemented. So we store the information that are passed to the object and use them to dynamically compute the "legacy" value. For now we only do this for the Pure implementation, as this is a good demonstration for the logic is fully insulated. The next step will be the update the C code too, to implement the various method with the new attribute (instead of the legacy one) and then start seriously thinking about the parameters we feed into DirstateItem. Differential Revision: https://phab.mercurial-scm.org/D11364

dirstate-item: have all the logic go through the v1_ accessors We are about to change the internal attribute. Having all the logic using the old "legacy" accessors will help to have a smooth transition. Differential Revision: https://phab.mercurial-scm.org/D11363

dirstate-item: drop the deprecated __getitem__ variante This is deprecated since 5.9. Differential Revision: https://phab.mercurial-scm.org/D11362