dirstate-tree: Make Rust DirstateMap bindings go through a trait object This changeset starts a series that adds an experiment to make status faster by changing the dirstate (first only in memory and later also on disk) to be shaped as a tree matching the directory structure, instead of the current flat collection of entries. The status algorithm can then traverse this tree dirstate at the same time as it traverses the filesystem. We (Octobus) have made prototypes that show promising results but are prone to bitrot. We would like to start upstreaming some experimental Rust code that goes in this direction, but to avoid disrupting users it should only be enabled by some run-time opt-in while keeping the existing dirstate structure and status algorithm as-is. The `DirstateMap` type and `status` function look like the appropriate boundary. This adds a new trait that abstracts everything Python bindings need and makes those bindings go through a `dyn` trait object. Later we’ll have two implementations of this trait, and the same bindings can use either. Differential Revision: https://phab.mercurial-scm.org/D10362

remotefilelog: use the correct capability when using getfilestype threaded The functon was overlooked when the capability was renamed Differential Revision: https://phab.mercurial-scm.org/D10673

test-copies: test that copies' sidedata can get computed during push If the source of the push does not have the necessary sidedata but the server needs them, the client should compute them on the fly while pushing. Differential Revision: https://phab.mercurial-scm.org/D10350

test-copies: test that copies' sidedata can get computed during pull If the source does not have the data, the pulling client should compute the necessary side-data while pulling. Differential Revision: https://phab.mercurial-scm.org/D10349

test-copies: test that copies' sidedata does not get corrupted during push This is an important usecase. Differential Revision: https://phab.mercurial-scm.org/D10348

test-copies: test that copies' sidedata does not get corrupted during pull This is an important usecase. Differential Revision: https://phab.mercurial-scm.org/D10347

test-copies: simplify some conditional output Now that all computation using sidedata give the same result, we can simplify conditional Differential Revision: https://phab.mercurial-scm.org/D10346

sidedata: move documentation about sidedata helpers to sidedata module Differential Revision: https://phab.mercurial-scm.org/D10361

sidedata: move sidedata-related utils to the dedicated module Differential Revision: https://phab.mercurial-scm.org/D10360

sidedata: replace sidedata upgrade mechanism with the new one Note: this is split into a separate change (like some other patches in this series) because it's not easy to have all patches work 100% and this seemed easier for reviewers. When cloning or upgrading a repo, we may need to compute (or remove) sidedata. This is the same mechanism that is used in exchange, so we re-use the new system to simplify the code and fix the remaining issues (correctly dropping flags and handling partial removal, etc.). This also highlighted an issue with `test-copies-in-changeset.t` that kept sidedata categories that are not relevant anymore. They should probably be dropped entirely, but that would be for another patch. Differential Revision: https://phab.mercurial-scm.org/D10359