rust-matchers: add `IgnoreMatcher` This is a big change but all of the pieces call each other, so it makes sense to have this all in one patch. Differential Revision: https://phab.mercurial-scm.org/D7925

rust-matchers: add `build_regex_match` function This function will be used to help build the upcoming `IncludeMatcher`. Differential Revision: https://phab.mercurial-scm.org/D7924

rust-matchers: add functions to get roots, dirs and parents from patterns These functions will be used to help build the upcoming `IncludeMatcher`. Differential Revision: https://phab.mercurial-scm.org/D7923

rust-matchers: add function to generate a regex matcher function This function will be used to help build the upcoming `IncludeMatcher`. While Re2 is still used and behind a feature flag, this function returns an error meant for fallback in the default case. Differential Revision: https://phab.mercurial-scm.org/D7922

run-tests: restrict Rust thread pool to 3 threads during tests Differential Revision: https://phab.mercurial-scm.org/D8270

nodemap: make sure the nodemap docket is updated after the changelog It is better to have a lagging nodemap than a nodemap pointing to node that does not exists yet. (strictly speaking, the order was already right, however we make it more explicit). Differential Revision: https://phab.mercurial-scm.org/D8188

nodemap: make sure hooks have access to an up-to-date version We make sure hooks can read persistent nodemap data and that they access something up-to-date with the pending transaction. Differential Revision: https://phab.mercurial-scm.org/D8187

nodemap: track the tip_node for validation Differential Revision: https://phab.mercurial-scm.org/D8184